I've tried 4 cards now and still get this every single time.
An error has occurred.
Please confirm the status of any relevant options and then try again.
For details, please contact the Square Enix Support Center.
(Error code: 401)
Also I've tried a card from two different banks, also made sure I input all info correctly and even tried using the card I had already paid for two months separately before and all of them I get the same error.