Best solution to install a sense monitor in crowded electrical panel?
Don’t put this device on anything larger than a 20 amp circuit.
these monitors draw very little power and putting them on a large breaker is asking for problems if and when things go bad.
Use a 15 or 20 amp circuit to power the system then if the worst happens you won’t be rewiring the entire panel.
If your breakers allow 2 wires per breaker great add the monitor directly. If your panel only allows 1 wire per lug get a few inches of the correct sized wire for the breaker 20 amp use #12 or 15 amp use #14 wire  a few inches out use a wire nut or some kind of splice device to tie the original conductor your new jumper and the power to the monitor all together. Then put the other end of the new wire to the breaker (a splice in the panel is ok).
If you need voltage sense tap a breaker close to the main lugs.
The reason I said not to use anything larger than a 20 amp is if the power supply fails it would melt the wiring down before tripping the 50 amp bkr, as the wires melt down they usually cross others on the hot or neutral / ground and depending on the failure I have had to replace several panels for aftermarket equipment that went up in flames.
Most of these are measuring the current using current transformers (no actual contact to the wires but the meter and transmitter need power)
Your garage door should not be on a 50 amp breaker in any case.