I'm not able to search for calendars when I do that, though. Change the Folder Type to Calendar, then you can search for the calendars by name. You can see if the calendar is in the list. I know how to do it on Outlook for Windows. I haven't found any documentation which specifically speaks to opening another user's non default calendar on Outlook for Mac. I have no problem opening the other user's default calendar, but I can't seem to find where you can access the other user's other, non-default calendars.
The environment is hosted Exchange via Office 365. I've got Outlook 2016 for Mac installed on a user's machine, and he wants to open up a couple of shared calendars from another user's account.
