No any prompt, in the general tab we have just found the same message of
the picture below that the "fortitray was blocked" (bottom message) and
we clicked on allow button then we tried again to start forticlient and
now it was working
We solved yesterday by simply allowing FortiTray in the General Tab of
Security & Privacy as described in this link
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.