https://superuser.com/questions/1127715/is-it-possible-to-install-forticlient-5-4-1-or-5-4-2-on-mac-os-sierra
So it's been quite a long time, and we still can't use the install
button on MacOS Sierra. There's just no excuse for this.
Hi! I have a MacPro 2013, and I just upgraded to Sierra. I then tried to
install the FortiClient, and it doesn't work. I downloaded
FortiClientOnlineInstaller, and ran the app inside. It says it's
downloaded the app, and there's an "install" button. ...