[keycloak-user] register new user; redirect to specific client url

I have an app secured by keycloak. Going to a secured page brings up a keycloak login page and the correct user/password gives the expected results. Within the client, I have switched on user registation. So now the login page shows a register link, which displays another keycloak page allowing the user to register with name, username, email. This "works" in that the user is added to the keycloak user database. But the application displays the error page because a role is not mapped to that user in keycloak. What I would like to happen is to be able to add the new user to the apps own user database, associate a role with the user, perhaps do some verification of the user. So I don't really know what keycloak is sending back to the app except that it eventually leads to /error. Is there a way to tell keycloak after a new registration contact this url where things can happen within the app? I realise that I could set a default role. But I really want a way of telling keycloak to go to a specific URL after a new user registration is completed. Regards,