I hate these chips after a multi-year crusade to get one to work. I've bought 3 different variations of it on breakout boards (SparkFun, DFRobot, and another one off of Tindie) and spent 10s of hours fiddling with them trying to get them to work with no luck. That includes multiple attempts at tuning the antenna and calibrating the capacitance, tuning all the other detection parameters, multiple different microcontrollers, several different power supplies and physical arrangements etc in case of interference. Anything and everything I could think of and test.

Everything I did failed and I have never been able to get anything other than noise out of these sensors at best. YMMV, as I know these chips have a history of problems but supposedly do actually work. After I finally gave up on these things I ended up getting an Acurite 06045M, a cheapo SDR dongle, and a Pi Zero W running rtl_433 for like $60 and that has worked perfectly for years and is fairly straightforward to plug into Home Assistant over MQTT. It very reliably detects strikes and gives a pretty good estimate of distance (but NOT bearing), plus you get an outdoor temp/humidity sensor for free.

I think the 06045M might actually use the AS3935 internally so presumably you can get them to work and when they do work they work very well, but nothing I could do as a (pretty advanced and well-equipped) hobbyist could make them work, and I've heard others had similar issues with them. So maybe stick to buying something commercial with it inside?

I was heavily involved with the local soccer community, and as a coach/referee I carried my own detector that I paid less for a ready to go version than this DIY shield. I was not going to depend on someone else's gear functioning when these were so cheap.

They do but without information from additional locations all you can get is distance and sometimes direction (dependent on specific chip / circuit). The ones with direction will probably good enough for most boating awareness situations.

If you want to know more specifically you need to have separate sensors that have with reasonably synchronized clocks so they can trilaterate or triangulate strike locations. Those sensors probably need to be further away from each other than most boats allow for. The further away the sensors are from each other, the tighter the time synchronization between them, and the more sensors you have will determine the overall accuracy your system will be able to attain.

My understanding is that lightningmaps.org is owned/operated by Blitzortung (see the upper right corner of lightningmaps.org).