What is the on-boarding process for Metro Bank's fans that use my application?

The on-boarding process is fully automated.

When your application makes a request to the /authorize resource, the customer is redirected to Metro Bank's secure authentication portal.

The customer shall provide any necessary account consent and payment initiation consent via the portal. When that process is complete your application can make further account information and payment initiation requests. The details of the authentication and authorization set up process can be found at the Authorisation and Authentication section.