CrushFTPDrive is an enterprise only feature.

It lets you connect to the CrushFTP server as a normal server drive on your machine.  So on OS X this will be a network drive on your desktop, and for Windows this will be a M: drive, or other letter of your choosing.  From there on, it acts like a network volume.  You can copy files to and from it, edit and work on files directly on it, etc.  Its not using WebDAV, and its built in caching system makes many common network operations very fast as it doesn't need to keep asking the server for information again and again.

Behind the scenes, it looks like a SMB/CIFS server item to the OS, but its actually talking to the CrushFTP server entirely over HTTP(s).  The client is deployed through a single click download link on the WebInterface, and it can be branded for its logo, and application name.  Its localizable too with all strings being editable.  Windows users need to install the included 'helper' service to work around OS limitations, but its a one time operation.  The client is self updating every time its launched.  You can reach Gigabit speeds through it on a LAN, and on latent networks, the CrushTunnel integrates with it to provide faster full network speed copies even for a drive that is half way around the world.

Identical features on OS X or windows.

Add the button in the user manager to allow downloading of the CrushFTPDrive program.\\
Then the user can fill in the connection information to connect the drive.  Screenshots for OSX and Win7.\\

After its connected you have the drive on your desktop for OS X, or as a drive letter in Windows.\\
The menu bar in OS X has the icon for CrushFTPDrive to control it.  Windows has the same in the systray.\\
In most Windows versions, you must install the helper service, and possibly reboot the machine one time.  This is so CrushFTPDrive can obtain the localhost port it needs for SMB.  This is a one time action, and CrushFTPDrive helps you through that process.  The windows service then processes connections for localhost SMB and gives them to CrushFTPDrive.\\