Every module in Microbizz has a set of permissions, which is the case for the Calendar module as well.
For a general understanding of permissions visit this section. The screenshot below may not be up to date.
iCal-link: This controls access to the ICAL LINK menu
Appointment types: ALlows access to editing of appointment types
Resources - overview: Allows access to the overview of resources
Resources - Edit: Allows access to editing resources
Filters: Who has access to configuring filters
Fields: Who has access to custom fields setup