Do you use VPN? If so, delete the VPN profile in Settings/General/VPN & Device Management/VPN. Don't just turn it off; delete the profile.
Not all cards can be used with the App Store, that’s a choice of the card issuer. So start by checking with the issuer to see if they accept cards for use in the App Store. Are you getting a “declined” message? A “card declined" message means that the issuer of the credit or debit card you have on file in your iTunes account rejected a charge or account confirmation, or the confirmation never got to the issuer. It is not an Apple problem; Apple is just passing through the message from your issuer. There are a number of reasons the charge or verification might be declined:
- Apple is not allowed to accept credit or debit cards in your country
- The card is not recognized in your country
- Insufficient balance or account in arrears
- Account suspended for suspected fraud (not necessarily by you)
- Error in card number
- Wrong expiration date
- Wrong security (CVV) code
- Address in your iTunes account does not match exactly the billing address for the card
- If you are trying to add the card to the Apple Wallet the issuer doesn't support the Wallet
- The card was not issued in the region of the iTunes store
- You are connected through a VPN provider that does not terminate near your actual location.
Here is additional information from Apple→If your payment method is declined in the App Store or iTunes Store - Apple Support
Related issues for specific messages: