Supabase I set up an authentication with, it was pretty straightforward. I was following this: https://github.com/vercel/nextjs-subscription-payments?tab=r...

Do you have suggestions for once users are logged in, for them to be able to submit a selection?

The most complicated use case is, each user can purchase multiple entries to a fantasy football contest. And then each week, each user should be able to submit their pick for each entry. The players available for selection each week differ per entry.

The most basic use case is, users login and get authenticated, and then on the Account page (which is included in the above linked repo), users can submit their picks manually, through like a Google Form.