But for some reason, I cannot select a build - Why not? What is stopping you? What happens when you click the plus button and the popup appears with the various builds listed? You're telling us you cannot select a build for some reason, but you don't tell us what's actually happening, so we can't actually help you. Have you added the translations? I think it requires at least one translation, even if it's just English. I think that's in the App Store Localizations bit. Take a look at the Help pages: https://developer.apple.com/help/app-store-connect/ There is a section on Managing Subscriptions.
Topic:
App Store Distribution & Marketing
SubTopic:
App Store Connect
Tags: