Metering a 240V 40A circuit with an Efergy Engage meter
The manual is absolutely nuts! There is absolutely no explanation of the wires to be monitored except a series of simplified diagrams of different panel types. And what color do they use to indicate the wires to be monitored? Black? Red? No! Green! I'm sure they picked green to match their logo and because &quot;environmental&quot;, but green is ground, the world round. If someone decided to actually put a monitor on their ground wire they would (hopefully) measure nothing. Argh!!!!
That being said, it is clear enough that you need to monitor 1 wire if there are 2 (the second would either be neutral or a second hot, and either way the same current as the first wire) or 2 wires if there are 3 (i.e., the 2 hots but not the neutral). Your red, black, beige is really red, black, white, with red &amp; black being the hot wires and white the neutral wire.
Put clamps on the red &amp; black.
In reality, since this is a car charger, you should have nearly all usage at 240V. The only thing running at 120V (if anything) would be some minimal electronics controlling the charging. But if there were anything significant on white, which there normally would be if these three wires were going into a breaker panel rather than into a single receptacle, the current on white (neutral) would be the difference between the black &amp; red (hots) and the monitoring system would handle it all correctly.
The last step is that the monitoring system needs to &quot;know&quot; what type of circuit you are using. If the system is smart enough (can't tell from the minimalist manual) then it should actually be able to figure out that the two clamp sensors are two halves of a 240V circuit. But I would suggest seeing what the system shows when you are actually charging. There will be some minor differences, but if you charge up your car 50 kWh, you should see very close to that amount (slightly higher due to conversion losses) recorded on the monitoring system.
From a deleted-answer-that-should-have-been-a-comment:
I'm curious why the HOA is asking this. What business is it of theirs?
That is actually pretty straightforward to me. If the charger is powered from a shared garage or parking lot, the power is paid for as part of the condo. fee (or equivalent - terminology varies). Everyone needs the lights and the access system, so the electric bill for the shared areas gets split evenly across all the units served, or by square footage of individual units or some other reasonable method.
A car charger, used by one unit out of many, drastically changes things. While an electric car should cost less in the long run than a gasoline powered car, the energy isn't free. Tesla started with free supercharging to get people to buy their cars. Once sales picked up, they dropped the free supercharging because people would buy cars anyway, knowing that a stop at a supercharger would be comparable to buying a tank of gas. A 50 kWh charge (1/2 to 2/3 of a typical Tesla battery capacity) typically costs $0.10 to $0.20 per kWh = $5.00 to $10.00. Not a big deal if it is once in a while, but if someone charges that much 3 times a week, it could be as much as the entire rest of the electric bill for lights, security system, etc. The HOA is right to be concerned and to want to manage the costs equitably.
If there is only one car charger then it is actually still pretty simple - subtract last year's usage from this year's usage (seasonally adjusted by matching the month) and you have a reasonable approximation. But once a second car charger is added - and one user charges daily for 100 mile round trip, but the other charges less frequently because they have a short commute, etc. - it becomes impossible to guess.
However, in addition to the complications that OP has found trying to DIY an electric meter, there are potentially regulatory issues involved in submetering. That becomes a legal issue for the HOA. I am sure we'll be hearing more of such things over the coming years as car chargers become more common.
A fantastic technical solution would be for the charger itself to monitor usage and report it. I suspect that some indeed do that, but of course that is a feature not needed for a charger at a single family home or provided by an employer for convenience of their employees, so manufacturers will likely not include such a feature unless/until there is a demand. (Which gets into peak demand pricing, but I digress.)
Use At Your Own Risk
To follow up on @Harper's excellent (as usual) rant answer, there are serious legal and possibly safety issues with this product. From the FAQ page:

Warning
There is no need for an electrician to do this power consumption meter install, as we are not disconnecting any wires. Please take care when removing any covers in your fuse circuit box. There are live cables here, either 110V or 240V or if using 3-phase power possible 415V. This is dangerous and electricity can kill so be careful. It’s a great idea to isolate all power beforehand from the main circuit breaker.

This has numerous red flags:

I suspect they recommend against having an electrician install because a licensed electrician is likely to tell you to return the product!
Nothing should ever say &quot;110V or 240V&quot; - be consistent. Either &quot;120V or 240V&quot; or &quot;110V or 220V&quot;.
It's a great idea to isolate all power beforehand from the main circuit breaker. Your average homeowner will have no clue what that means. It is CYA-ish language, at best.
fuse circuit box is very old terminology, at best. In fact, the diagrams I saw in the manual all appear to (rightly so) show modern-style circuit breaker panels. There are still plenty of fuse boxes around (typically in houses more than 50 years old that haven't had major electrical renovations) but that is poor terminology choice.

In fact, aside from the legal issue, there are real safety issues. If you know what you are doing, putting clamps on the wires is a trivial process. But when doing so in the panel you are literally inches away from unprotected (or overcurrent but not GFCI-protected) wires. So this is an inherently dangerous activity. In fact, the specific type of activity where I would, personally, recommend that most people call an electrician rather than DIY - as opposed to replacing switches, receptacles, etc. where DIY can be done quite safely with minimal training.
My description about (clamp red &amp; black, why the HOA wants it monitored, etc.) all still apply 100%. But beware of any product that not only isn't properly listed but appears to care very little about safety. It is possible to have a product, especially one-off or niche products, that are designed well and 100% safe, just not listed/certified due to the expense involved. This does not appear to be one of those products.