Build a Basic CRUD Application with Grails and Okta

I am trying to integrate a grails application with okta. I followed this example in git hub where I see you as one of the contributor.

I have some isuues when I tried this. This example has a requirement where in I need to create/link the remote oauth2 account to local user account after successful authentication by okta. I do not want the overhead of maintaining a local user table again. Is there any way I can surpass this? And just go to the home controller page directly bases on the user roles. I am able to get the group claim in the okta jsonn output. How do I map this user response to Grails domain user/role class? Please help me with this

Could you please please help me with this?