Hi agrotz,
Follow these steps to find the Delegation tab. In the Calendar app on your Mac, choose Calendar > Settings, then click Accounts. You should see an Account Information tab, then right next to it, the Delegation tab. You should then be able to follow these steps to view the calendar accounts you have access to: Share calendar accounts on Mac.
See calendar accounts you have access to
1. In the Calendar app on your Mac, choose Calendar > Settings, then click Accounts.
2. Select the calendar account, then click Delegation.
• A CalDAV account appears in the “Accounts I can access” list.
• For an Exchange account, click Add button , then enter the user name of the person who gave you access.
3. To see a delegated account’s calendars in the main Calendar window, select Show.
4. To see a delegated account’s calendars in a new window, choose Window > [account name].
Regards.