Give Users the ability to create folders

Hi Peter, 

Welcome to Box Community and glad to help!

In order to allow your managed users from creating their own folders. You should disable 'Restrict Content Creation.' 

To do so, kindly follow these steps. 

• Login to box.com and go to Admin Console> Enterprise Settings. 
• Select the Content & Sharing tab and scroll down to Content Creation and uncheck Restrict Content Creation then Save.

Hope it helps!