Select the ‘Folders’ option in Outlook (Note: **this will vary in appearance depending on the version of Outlook**)
Expand “Public Folders” -> “All Public Folders”
Expand the specific folder, right click the item and select “Add to favorites”
The calendar will now show in your list of calendars:
In the redesigned user interface in Microsoft Outlook, you see that:
The horizontal navigation bar that was at the bottom of the Folders view is now a left-side vertical navigation bar.
The ellipsis icon on the horizontal navigation bar is now a More Apps icon on the vertical navigation bar.
When you select Folders, the navigation bar shows a Folders icon. To permanently pin the Folders icon to the navigation bar, right-click the icon, and then select Pin.
If your Microsoft Outlook app was updated to the new Outlook for Windows, you need to add public folders to Favorites before you can access them. Use the following steps:
1. Right-click the name of the account and select Add public folder to Favorites.
Notes:
In the pane that displays the public folder hierarchy, expand All Public Folders.
Select the public folder that you want to add to Favorites and then select Add Public Folder.
After the public folder is added, go to your Calendar to access it.