I am trying to set up a subscription on the mogstation for my account using a credit card, but i keep getting this error:

An error has occurred..
Please confirm the status of any relevant options and then try again.
As repeated registration failure can lead to restrictions being placed on your account, we strongly recommend that you contact the Square Enix Support Centre for guidance before attempting to register a Credit/Debit card again.
If you are registering a payment method with a payment service provider like ClickandBuy, please contact them directly.
(Error code: 601)

How to fix?