You also need to put it on itch. "Upload new project" from the menu next to your display picture, follow the instructions there, and make it public, then come back to the GitHub Game Off jam page - when it starts, there will be a "submit your project" button. Press that and it will be added to the jam ☺️ submissions will be closed when the jam ends, so you've gotta submit before then otherwise you won't be part of the jam