Have you checked the instructions on how to Link the bank card?
There are several reasons why your card might not be linked:
First, you need to go through the verification process.
After that is done, please check if your card is of the Mastercard (for EU) or Visa type, and 3D Secure (see “What is 3D Secure?”). Also, please note that you cannot link virtual cards.
In case the base currency of your account is not EUR/USD, please make sure that you're entering the USD/EUR verification amount and not the amount in the local currency.
Apart from Cryptology’s requirements, there are numerous factors that might affect this process, such as bank decline, card limit reached, incorrect card data, or bank malfunction.