Various ways this can go, based on some details not yet known here…
If you don’t know the postal code (or zip code) associated with the payment card specified, check with your financial provider.
If there’s no postal code associated with your shipping address and thus with your payment card, and if your Apple ID is set to your country or region, and you’re getting required to input something that doesn’t exist, you’ll need to check direct with Apple, as mentioned above.
If you’re trying to use an Apple ID and a payment card associated with a different country or region than your currently located, you’ll need to use the matching address. These setups do tend to get detected by and blocked by Apple if in ongoing and not transient usage, though.
Apple Gift Cards can provide a means to avoid using a payment card from elsewhere, if that’s the issue here.
There are a few countries where Apple is legally not allowed to operate, too.