Is it possible to use the appointment scheduler with those in the course who are not students (non-editing teachers, managers, course creators, other teachers, etc)? What about a person who has guest access?
Scheduler can be configured in this respect via capabilities. By default, students have the capability "mod/scheduler:appoint" (which allows them to book appointments) and teachers have the capability "mod/scheduler:manage" (which allows them to set up slots) but you could assign this to any other role.
What does not work well is people having both the capabilities to set up slots and to book slots.
Guests will not be able to book slots, as the slots need to be associated with a user.