Fortigate and Fortiauthenticator authentication saml sso gsuite

hi everyone

i want a help from you please

i'm working inside a company that have 1 fortigate 200D and 1 FAC 400E and 7 fortiap 224e outdoor

we use saml sso with gsuite as a type of authentication for all users in the campany (10 000 users max and 2000 per day)

we have a serious problem with this authentication using google chrome on mobiles and laptops clients

i think this problem is on the certificat that google chrome does not accept or other thing 

the error message on google chrome is as follows (french) :

Le site google.com est actuellement inaccessible car il utilise la technologie hsts. les erreurs réseau et les attaques sont généralement temporaires . Vous devriez donc pouvoir accéder à cette page plus tard.

in english

The google.com site is currently inaccessible because it uses hsts technology. network errors and attacks are usually temporary. You should therefore be able to access this page later.

this message that google chrome give to clients is showing when trying to access in the portal gsuite for authentication with a gmail account using a domain of the company

please help

thank you.