Access Group in the service package points to PPRC:Administrators. Member of this group is "Administrator@pega.com", with password "install" (at least I think so). I also added my user to this group, no luck either. My user has also the role PegaAPI, which has all the privileges needed (pxCreateCase(5), etc.)
Whether I use the internal Swagger, or postman, I get a 401 whenever I try any option.