Setting up Development Platform

Hello,
I am trying to set up a code development platform on windows. I followed the instructions on ardupilot github webpage on MAVProxy for development on windows platform. I was successful in setting up all the dependencies to run mavproxy. I am now confused between ardupilot and ardusub because the mavproxy source I downloaded from github contains modules which seem to be for the air vehicle.
How do I get modules which are for the underwater drones? Do I need to download the Ardusub source from github?
I only need the modules for underwater vehicles so that I can use the code snippets to develop my own modules.
Thank you in advance.

Most of the modules are for all vehicle types, some are intended only for aerial vehicles, but there aren’t any specific to underwater vehicles.