Please follow the below steps to share your Outlook Calendar with colleagues.
Share your calendar
- Open Microsoft Outlook.
- Select Calendar > Share Calendar.
- Choose a calendar to share.
- Select Add, decide who to share your calendar with, and select Add.
- Select OK and you’ll see the added people with a default permission level.
- Choose a name, select the access level to give, and select OK.
A video guide is also available from here