A quick addition to this post. The auto generated access groups seem to be cloned from an OoTB access group - CRMForAdvisor:NBAADevelopers.
Even this access group seem to have only two portals configured, 1) Developer, 2) CPMInteractionPortal. But the implementation guide says that the default portal of this access group is the app studio.
Excerpt from the implementation guide:
Creating operator accounts The New Application Wizard for Pega Next-Best-Action Advisor creates the following default access
groups: <your implementation application>:NBAADevelopers This is an access group for administrators. The default portal for operators in this access group is the
App Studio. This access group also grants access to the Interaction Portal.