Here is the procedure to add Public Contact to your contact list on Outlook
1- To access the public folder, go to Outlook -> 3 points (...) -> Folders
2 - Afterwards, you will see appear on your Outlook (Public folders - your email) -> go to all public folders -> global contact -> the contact list will be here (it has the name Global contact)
3. Right click on the contact list Global Contact -> add to favorites
4. Afterwards, you add
5. Go into contact -> other contacts and all contacts are going to be on this.