This error message indicates that your payment method is not linked to a bank account. 

If you click into a users profile via the Admin Settings > Users tab and scroll down to their payment method. You can click into it and assign the bank account (screenshot below).

How to add a bank account in Xero:
1/ Go to Accounting > Bank Accounts tab
2/ Click on 'Add Bank Account' and follow the steps

Did this answer your question?