Affiliate plugin setup with Pro Sites, especially payments to affiliate

I am really confused here. I searched for help and found some threads but none answered my questions and one or more referenced the Supporter plugin which was confusing.

I have a multiuser site with the Prosites plugin added, I installed the Affiliate plugin and now want to get it working. In Prosites, I set an annual price of $27 and nothing else. No free sites will be offered.

My problem is how to set the Affiliate plugin so that the affiliate receives a 50% commission for each paid referral? I looked at the affiliate settings and saw some payment settings at the bottom but I see no way to have a 50% commission anywhere and I do not understand how to use those payment settings.

I am really desperate for help here because I cannot launch my site until I get a fully functioning affiliate program setup and working.

Thank you far any help and suggestions.