You can add a new user (subscriber) and assign a manager immediately bu going to the Users page in wordpress dashboard and click Add New:

 

Now you can fill in the info for the new user and assign them a manager. You can choose to leave this field for later too.

 

 

Now this user will automatically have a folder created under the manager folder that you selected.

 

You can now log into the manager account and you will see this user’s folder, you can now ready to add files to share with this user now:

 

 

Now if this subscriber (jamal) logs into their account, they will see this folder too:

 

Any folders/files the manager shares with this user will appear here.