Recently banks have introduced more security checks when spending online. When you join your game through the subscription / card payment process, its likely you will be asked during the process to approve your transaction, or prove its actually you spending. The latest version asks to AUTHENTICATE your card. You do this by opening your banking App associated with the card, and licking approve in the notifications. You can the return and complete the process. Quite often your bank may send you a push notification, which you can also click to speed things up.