Hi Stillstuck2024,
welcome to the Apple (user-to-user) Community!
Re: "Payment methods :
why do I have to have 2 payment methods in order to be able to use AppStore?"
We are all Apple users, like yourself, in the community. We have no access to your accounts or details. Apple just does what Apple does. No-one here can speak for Apple.
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Re: it’s not letting me purchase unless I add credit card account
- what if I don’t have a credit card?
See which payment methods Apple can accept in your country or region:
Find your country: Payment methods that you can use with your Apple ID - Apple Support
In some cases, for particular purchases, Apple requires a credit or debit card on file. This can be required, even if you use an Apple Account balance to make the purchase.
Eg: What you can buy with your Apple Gift Card or Apple Account balance - Apple Support
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If needed: How to: Add a payment method to your Apple ID - Apple Support
or
Remove a payment method from your Apple ID - Apple Support
or
Add money to your Apple Account balance - Apple Support
Trouble-shooting: What to do: If you can’t download or update apps - Apple Support
More info / support / contact options:
App Store support website:
App Store - Official Apple Support
All the best :-)