I need some help figuring out how to make sure I have the right package for me to have 20 people submit a form and pay a registration fee

I checked your account and I can see that you are under the Silver plan. In this plan, you can receive 100 payments per month.

This is the right plan for you if you are expecting 20 payment submissions.

I also recommend you check this article: Understanding-Your-Account-Usage-and-Limits.

Hope that helps. If you have any questions, let us know. Thank you.