am having problems when trying to subscribe to the workspace it gives the error "This payment method can not be used to complete this purchase" during payment
Have you tried a different one? Do you already have a payment associated with pay.google.com? If so, maybe try the payment that is in pay.google.com? One article that may assist with what payment options that may be available: https://support.google.com/a/answer/1230192?hl=en.
I have the same concern. "This payment method can not be used to complete this purchase."