saw an answer from SE when you look in the dev tracker, but in French.
i put it in google translate:

Hello everyone,

If you have 601 or 401 errors, please please contact the Assistance Centre and select the category Billing and Payment subcategory.

So that our agents help you in the most efficient manner possible, please kindly provide the following information with your request:

• The error code you encountered
• Your login Square Enix Account
• The selected payment method
• The type of card used
• The country of origin of the card
• The name of the bank from the map
• The number of times you tried to process the payment after receiving the initial error message