Source means the files for the game. The user needs to be able to download your source and run it from the engine.
Submissions need to be free.
So I just went through the submission process. I downloaded a zip file that had the game.exe and the game.pck. However I did not see anywhere I could download the "source". I am using godot engine. It seemed to go through ok but I wanted to make sure I was uploading according to the rules. I would appreciate any help with this.