but here's my stab at it.

Awesome Keith!!! I could be wrong but I believe you're the same Keith Ammann from "The Monsters Know What They're Doing", which was a game-altering blog read for me (I sang its praises in a tweet a few years aback) - if so, and even if not, it is an honor to have you here :)

The submission process is basically:

1. Click on your Account on the upper right corner
2. Click on the "Upload new project" under the Create section
3. After created, navigate to this Jam's submissions page: https://itch.io/jam/ttrpg-system-agnostic-badge/entries
4. From here, you can submit your project

It s a smidge painful, but I think Itch.io does this so it can create data entities for your project separate from this jam, so there is a clean line of ownership and origin :)