Apple is checking with your financial institution if the payment method is valid and receiving a negative, or no, response. Make sure the name and address are entered exactly as it appears on your financial institution bills and that the 3 digit CVV is correct. Check with your financial institution about the status of your card.
Use the document Add a payment method to your Apple Account - Apple Support to review your payment methods such as credit or debit cards.
On a mobile device:
1. Open the Settings app.
2. Tap your name.
3. Tap Media & Purchases, then tap View Account. You might be asked to sign in with your Apple ID.
4. Tap Manage Payments.
Check there are not any problems with your payment method. They will usually appear in red lettering. If there are, make sure what you have entered is correct and exactly matches what is on your card and address. If it is, contact your financial institution. Problem methods will usually have a notice in red lettering below them. The article: If your payment method is declined in the App Store or iTunes Store - Apple Support has some information about declined payment methods.
- Make sure your payment method is up to date or to try a different one ( If you need to change or update your Apple Account payment method - Apple Support ).
If you cannot see a reason for a problem and you have contacted your financial institution, you may find the fastest route to resolution would be to contact Apple for assistance with this.
To contact Support, click on this link and choose a method —> https://getsupport.apple.com/?caller=cups&PGF=PGF63006&category_id=SC0060