I am struggling to understand what it wants me to do to sync my Google Calendar to my calendar app on Zorin. How does this work?
So I assume what you're talking about is the built in calendar, as captured here:
If you click the hamburger as I have in the calendar app, it will ask for online accounts.
This will then open a settings window bringing you to the online accounts section, where you can login to whatever accounts you want (including google, microsoft, etc). Once you're signed in there, it should automatically populate the calendar with yours from google.