I need help *buying* music from iTunes. It will *only* let me pay the monthly subscription fee. Anybody know how to fix this?

The Music app is used to listen only, and it'll offer the Apple Music subscription if you try to listen to something you don't have. Use the iTunes Store app to buy things.

Are you sure you're looking in the right place? Apple has 2 services: Apple Music which is a streaming service that you pay every month and iTunes, which is an online store where you can buy media.