Outlook Calendar Access

HOW TO SHARE YOUR CALENDAR:

Go to Office365.com and sign in then select the Outlook APP. Click on the Calendar icon, select the ellipsis for the menu, then click on Sharing and Permissions.

2. In the dialog window, Enter the email address of the user you want to share with.

3. Set the calendar permissions for the user by clicking the down arrow and choosing a permission setting. A Delegate can act on your behalf.

HOW TO ACCESS A SHARED CALENDAR (MAC)

To access a user's calendar, User that has access needs to add user who needs access as a delegate in his Outlook and assign with the access permission to calendar only.

Select the File tab, then select Account Settings > Delegate Access.
In the dialog, select Add.

If Add doesn’t appear, an active connection might not exist between Outlook and Exchange. The Outlook status bar displays the connection status.
Type the name of the person whom you want to designate as your delegate, or search for and then click the name in the search results list.

Note: The delegate must be a person in your organization's Exchange Global Address List (GAL).

More Resources:

https://support.microsoft.com/en-us/office/allow-someone-else-to-manage-your-mail-and-calendar-41c40c04-3bd1-4d22-963a-28eafec25926#__toc305134742