Setting a Default FTP folder and 0GB Storage Quota
Setting a default ftp folder will force the user to land in the specified folder upon clicking the Files Tab and setting a 0GB storage quota disables the user from being able to create and upload into their root directory. This does, however, not prevent the user from being able to upload into shared folders. This creates a restricted and directed workspace to smooth workflow and file transfers between your remote site and restricted users.

To setup a default FTP folder, follow the instructions below:
Create a folder you want to use as the user’s default remote directory.
Alternatively, if you already a folder, you can skip to step 2.
Go to the Users Tab and create a new user by clicking Add (add user by email) or Add Username (does not require email) and fill in the users credentials.
Check “Add storage quota” and set it to 0.
In the options field, scroll down to “Default FTP Folder” and input the name of the folder you selected in step 1.