How to add delegate calendars using Google Calendar?

NotePlan syncs with your calendars using Apple's Calendar API (iCal). You can add accounts in the "internet accounts" or calendar accounts preferences of the Apple Calendar app or in the system preferences. 

If you don't see your delegated calendars from Google, you can add them in the Accounts settings of the Apple Calendar app:

You may need to restart NotePlan after enabling some calendars.