You can enable AMPI in the admin panel > B3_organization > organization > General Settings & Features
You can set the default access group to users who register in the admin panel > B3_organization > organization > User Roles
This role will be assigned to all users that sign up with site. Either:
no default AMPI role is defined (user needs to be individually added to AMPI)
user is an AMPI user
user is an AMPI expert