In the wordpress dashboard find the Users page under the File Manager menu:

You can now click on Folders infront of a user and assign them any folders and permissions from the list:

You can now view all these folders in your File Manager page and you can share these folders in the front-end with the shortcode:

[filemanager foldername="*"]

This shortcode will display all the folders assigned to the user who is viewing it.

PS. The folder named “/” at the bottom of the list is the wordpress root folder.