Creating a SHARED GROUP CALENDAR in Exchange 2016

Evan KontosI would advise against using public folders. A Shared mailbox would certainly work, although as you mentioned the users would need to invite the Shared mailbox and by default would also need to accept the invitations.

That can at least be circumvented by enabling automatic processing, similar to a Room mailbox. To do so, run the below pwsh cmdlet:

Set-CalendarProcessing <Identity> -AutomateProcessing AutoAccept

Here are the defaults for reference:

AllowConflicts : False
BookingWindowInDays : 180
MaximumDurationInMinutes : 1440
AllowRecurringMeetings : True
EnforceSchedulingHorizon : True
ScheduleOnlyDuringWorkHours : False
ConflictPercentageAllowed : 0
MaximumConflictInstances : 0
ForwardRequestsToDelegates : True
DeleteAttachments : True
DeleteComments : True
RemovePrivateProperty : True
DeleteSubject : True
AddOrganizerToSubject : True
DeleteNonCalendarItems : True
TentativePendingApproval : True
EnableResponseDetails : True
OrganizerInfo : True
ResourceDelegates : {}
RequestOutOfPolicy : {}
AllRequestOutOfPolicy : False
BookInPolicy : {}
AllBookInPolicy : True
RequestInPolicy : {}
AllRequestInPolicy : False
AddAdditionalResponse : False
AdditionalResponse :
RemoveOldMeetingMessages : True
AddNewRequestsTentatively : True
ProcessExternalMeetingMessages : False
RemoveForwardedMeetingNotifications : False

Do note that this is how I would achieve the outcome using Exchange only. Obviously you could use Teams/SharePoint/M365 Groups. To your point about resource mailboxes, that would work though I like to keep my resource mailboxes strictly for resources.

Let me know if you need help, happy to assist.

Cheers

Daniel K