Just a heads up, a lot of people only deal with one specific operating system in their environments (Fortinet dumps a lot of their investment into the development of Windows applications because of the market share). Just in case you haven’t found it, Fortinet provides downloads to the Mac OS and Linux OS FortiClient applications in the firmware download locations of their support site. (VPN folder within the selected firmware folder).
Hopefully, this helps some of you out if you are in need!