I'm using the FS-BOX-V3.
To use the FS Box, navigate to FSBox.com and follow the instructions to download the client software.
OS X 11.3.1
If you are installing on OS X, like me, you will likely encounter an issue when launching the application. It will prompt for your system password, you'll supply it, then it will ask again and again until it fails and closes the app. I modified the file permissions of FS_Service_Core to resolve the latter issue.
From Terminal, run the following command.
chmod 755 ~/Documents/fs.box/core/FS_Service_Core