Methods of payment for online Apple Store, and iTunes Stores, are outlined as follows:
Payment, Financing, Refunds and VAT - Shopping Help - Apple
on a payment method below to find out more: ApplePay; Credit Cards or Debit Cards
//apple.com/shop/help/payments
• PayPal - from above section:
Payment methods that you can use in the iTunes Store, App ...
Before you can buy anything from the iTunes Store, App Store, and iBooks Store,
or join Apple Music, ... the accepted payment methods are Visa, ...
//support.apple.com/en-us/HT202631
The first linked-section above includes details about using PayPal to buy purchases.
Hopefully you can make use of that to further see how the system is set up. There
may be different methods or rules of payment, depending on your region or country.
Note: different rules apply to iTunes, App Store, and topics in section directly above.
On a separate topic, this applies where Apple ID & payment info is in your records:
Change or remove your Apple ID payment information
... iCloud, iMessage, the Apple Online Store, ... that you use your Apple ID. If you change
your payment method, ... payment wasn't accepted, ...
//support.apple.com/en-us/HT201266
Good luck & happy trails! 🙂