You can use the following link to add the MSTP calendar to your Calendar app on MacOSX: https://calendar.google.com/calendar/ical/vanderbiltmstp%40gmail.com/public/basic.ics
Go to Calendar>File>New Calendar Subscription and paste the above link.

Alternatively to add the MSTP calendar to your Google Calendar you can go to: https://calendar.google.com/calendar/embed?src=dmFuZGVyYmlsdG1zdHBAZ21haWwuY29t
and click on the +Google Calendar button on the lower right of the screen.