I guess this would be more of a question for the organizers, but some places I can think of are:
- The “Short description or tagline” field on the project page. I don’t remember how many characters you can fit here, but I think text put here might show on the list of the jams’s submissions, and possibly in more places, so I would probably put a short description here.
- The “Description” field in the “Details” section of the project page. This one can (and probably should) be longer. I think you can even add images in this one.
- Text files attached to the project. Here you could put longer things, such as a full transcript of the podcast if you want.
- I know that games can have a file that “will play in the browser”, and I imagine you might be able to use that to make the podcast listenable without having to “download” it. And you could theoretically also put text there.
- If the jam’s submission form has a field where it asks you to put a description there, I guess you can do that too. I wouldn’t leave the project page and short description empty though.