It isn't is the answer. Google/Apple Pay are not the app that would be used. Google wallet is merely a storage app for documents, usually things like tickets. As others have said, it would also be an email so you just open the document in that and scan code. That said, for younger kids with no phone at all, not sure how the club will deal with that but I'm sure they are aware of the problem.
The parents can just add the child’s tickets to their phone.