There may be multiple calendars in iCal/Calendar, depending on how you set up your Mac computer and/or if you use other Apple computing devices (e.g. iPhone or iPad).

When you configure your Microsoft 365 account, the calendars associated with it will be shown in a group. Use that group in the instructions that follow.

1. From the File menu select New Calendar.
2. Select your Mircosoft 365 account from the menu so that iCal/Calendar will create the new calendar as part of your Microsoft 365 calendars.
3. The new calendar will appear on the Calendars menu at the top left of the iCal/Calendar window with a default name of 'Untitled'. To modify the name, slow-click on the calendar and when the name is selected, type a new name.