Add using a linkYou can only add a calendar using a link if the other person's calendar is public.
- Open Google Calendar.
- On the left side, find "Other calendars" and click the down arrow .
- Select Add by URL.
- Enter the calendar's address in the field provided. The address needs to be an ICAL link.
- Click Add calendar. The calendar will appear on the left side under "Other calendars."
There are multiple ways to add one. See Google support pages for other ways!
https://support.google.com/calendar/answer/37100?hl=en