Payment not complete?
When I try and one load something from the App Store it tells me payment not complete even tho the app is free and I have checked my payment details on my apple id
iPhone XS, iOS 13
Have you tried signing out of the App Store/iTunes and then back in to see if that refreshes your account?
If necessary, contact iTunes Support. Either use the form or scroll to the bottom of the page in the 2nd link. Follow through the screens to get a chat or telephone option. You may need to pick a problem that is slightly different than yours to get a chat option.