You can enable access to the native filesystem.
To do so, simply edit Security.cfg and add/set the following line:

ShowServerFiles TRUE

then restart DeskNow.

After this, the admin account will have access to the folder [All server files]. Under that folder, the local file system will be accessible (for Linux/Unix/Mac, this means the / folder. For Windows, this means the list of all drives available to the account running DeskNow, typically LOCAL-SYSTEm. See below for more details).

Admin can then share some of these folders to other users, with the appropriate permissions. Use with care! 

Note that Windows has a limitation: network drives are mounted only when a user logins, so if you start DeskNow as service you must be logged in anyway as the user who has setup the drive mappings, otherwise they will not be accessible. This is a known Windows limitation.