Eddie,
Its very easy, or you can follow the steps to import your Outlook for Mac calendar to google calendar once the events are exported to ICS format.
1. Open google calendar
2. Now click settings in the top right corner.
3. Open calendar tab.
4. Click Import calendar event between my calendar & other calendars section.
5. Click choose file button and select the file you have exported. Make sure your file is in ICS format. Only then, it will be imported to google.
6. Set the calendar settings i.e in which calendar you want to import your event.
7. ATlast clicks on import button
8. Check the imported OLM calendar to Google calendar.
Check it out