Hi @UVEECSoftware -
The navlight.lua is only required for the BlueBoat - it blinks the output according to what mode the vehicle is in, so if you don’t need that functionality no need to download it.
To use Lua scripts, simply enable the SCR parameter (under autopilot parameters), and then place scripts in the correct directory - see more information here.
For your AUV, HAUV.lua script may have some relevant tricks! I’ll have a big write up on it (and general extension development) coming soon.
If you have a Navigator, all you should need to do is install the autopilot (ArduSub or Rover) to then be able to select SITL. Note that in SITL, you won’t see input/output from the Navigator - it’s all virtual!