If you are using a non admin account please refer the below link to give permissions to create Public folders using Outlook
How to Give Permission to a Client to Create Top Level Public Folder (Root Public Folder Tree) in Exchange 2010
You won’t able to use GUI or Power shell to create a public folder calendar
we need to use outlook to create that.
Right Click on Public Folder – New Folder
Type Name
Choose Folder Contains – Calendar items
Click on All Public Folders
Click ok
You have successfully created a Public folder calendar.
Maheshkumar S Tiwari edited Original. Comment: Added tags