This error indicates that there was a problem generating an Access Token. This error is related to invalid configuration ( Refresh token ) or an inactive Rabo Smart Pay account.
Keep in mind that the Rabo Smart Pay has a different set of configuration keys for each environment ( Sandbox and Production ).

Make sure to check the following configuration;

• Refresh Token

• Signing Key

• Are these for the Sandbox or the Production environment

If these credentials seem to be correct, contact the Rabo Smart Pay support team for the status of the account.