"Verify Contact Information" in Apple Pay
The support link doesn’t spell this out well, but in my experience this has always been about the billing address no zip code / postal code or other oddities where the data you enter for Apple doesn’t translate perfectly to the seller via API.

https://support.apple.com/en-us/HT204506

You want to add your phone number like a courier service (FedEx) would ring for delivery issues. Examine any odd characters in your address or postal code (in the US, Apple wanted zip+4 but I had to get them to remove it since many vendors couldn’t handle a - or more than 5 digits.
Sometimes you can add the info as a one time override right before paying. I’ve found that unreliable and fixing my info with Apple was more reliable of a fix.