Hi,

Well for end-users, there is no as such role needed, except for snc_internal role (which helps end-users to redirect onto Portal page after Login).

Now if you are importing end-users, through Data-Import, just make sure that you keep Run Business Rule check-box as true (i.e, checked), so that all users will get that Role.

If you are creating one, then either you can add that role manually, or even if you don't provide that role, it will automatically be assigned to that user because of a BR written over that.

Please mark my answer as correct/helpful in case that helped you with your query.

Regards,
Vishrut