You can find the verification code in the bank statement of your underlying card. The code can take up to 5 days to appear on your bank statement, depending on your card issuer. If you would like to know sooner, you can call your bank and ask for the reference. The code you need to enter will be in the format C-xxxxxx
If you haven't received the code after this time, it could be that your bank is blocking the transaction. If this is the case, please contact them to ask them to whitelist transactions with Curve.
Once you enter this in-app, your card will be able to be used with Curve.