How to add a Public Folder to Outlook Web App – from: Microsoft
Add favorite public folders in Outlook on the web
In order for users to access their Outlook favorite public folders, they must also add them to their Favorites in Outlook on the web. The Outlook client does not automatically sync public folders with Outlook on the web.
- To add a public folder in Outlook on the web, right-click Folders, and then choose Add public folder to Favorites. Locate the folder and click Add.