tricycle engine compatibility?
Most front wheel motors will work on the trike and will install in a very similar way. There are a lot of kits on ebay, ranging in price from a couple of hundred dollars up through sensible prices to quite silly. See this question for some opinions on the cheap kits.



Most crank motors will also work and be easy enough to install. This Sunstar kit, for example. The advantage is that it uses the gearing system on the trike, so it works better than a hub motor when the trike is going very slowly. The disadvantage is that it's a pedal-assist motors, so it only works if you're pedalling.



My suggestion is that you find a local bike shop that has experience with electric bikes, ideally one that sells kits, and get them to supply and fit a kit for you. While it's possible to do the work yourself, unless you have the rights tools and experience it's very easy to make mistakes and end up with something that's unsafe, doesn't work, or is unreliable.

You can also buy ready-made electric trikes like this one. It might easily turn out to be cheaper to do that than buy a trike plus a kit if you don't already own the trike.