When signing up, you’ll need to connect your bank account to the card twice. The first time is to confirm that you agree to share details with Currensea, and the second time is to set up the direct debit to pay for the transactions you make with your Currensea card.
If you’re having trouble beyond this, please send a screenshot over to help@currensea.com so they can investigate for you. Please note, you should connect your Debit Card to your bank account, not a credit account.