There are some quirks when it comes to integration between the Windows and Mac version of Outlook. For example, the normal “request access to calendar” process in the Windows version doesn’t work when you want to view a Mac users calendar. I figured out an easy fix though. If you can’t see the calendar of an Outlook Mac user in your environment then follow these instructions.
A Mac users name won’t appear by default in your list of calendars you can open. You must open the Mac users calendar first using the “open calendar” button in the ribbon at the top of the screen. The icon is a calendar with a green plus sign. Then choose "open calendar using address book” and then look up the person and select them from the list. Then near the bottom of this screen click on Calendar. Now that persons name will appear in your list of available calendars and you should be able to see the persons calendar information.