I had the same issue "No Updates" but as I had just time machine restored my iMAC the apps would not run that I had in the Application Folder, Restore from Time Machine did not work and I could not install a new version.
Tried to remove all the files I could about Forticlient but still no luck.
Luckily I had a very old copy of the Forticlient DMG so when I opened that it had the installer and uninstaller....so I ran the uninstaller and its said successful!
Then tried the latest updater that was giving me problems before and now it worked....I have the latest VPN up!
The Fortinet Security Fabric brings together the concepts of convergence and consolidation to provide comprehensive cybersecurity protection for all users, devices, and applications and across all network edges.