Hey Alex,
Welcome to the Apple Support Communities! I see you're having trouble utilizing the Apple Pay Instant Transfer feature and you're getting stuck when it asks you to add a card to set it up later, so I wanted help.
First of all, make sure you're in a country that supports Apple Pay: Countries and regions that support Apple Pay. If your country supports Apple Pay, it's also a good idea to try this while connected to a different network. If you've tried this while connected to a cellular network, connect to Wi-Fi and try again. If you are getting an error while connected to a cellular network, make sure to check that Wallet is enabled (green) for cellular in Settings > Cellular. I also recommend to make sure that your date and time are set correctly in Settings > General > Date & Time and that you aren't connected to a VPN while attempting to use Apple Pay.
Cheers!