Calendar settings (cog) → Share
The calendar creator can share the calendar with particular groups of users. Two modes are available:
Use-only (browse, add events, filter etc.)
Use & Edit – with the ability to manage the calendar settings and delete the calendar. Sharing and name editing are unavailable.
To access a shared calendar, a user should add it to the list of their favorites.
Add calendar → Add Shared
Shared calendars → Add
Now the shared calendar is available in the Calendar switcher menu.