This article will show you how to import calendar files into the Calendar App on Mac computers.
Who can use this feature?
System Administrator | Owner | Publisher | Author
Instructions
Navigate to your public calendar (/calendar.aspx).
Click More Tools:

Select Subscribe to iCalendar:

Click on the iCalendar feed you wish to add to your calendar:

Open the downloaded file.
Select a calendar to add the event to:

Click OK:

View the event on your iCalendar:

Note:
If you import the calendar, it only takes the events that were on the calendar at the time you saved the iCalendar file. It will not continue to sync and update.