Certificate error SAML Captive Portal

Wireless Authentication using SAML Credentials and Azure as IdP
Hello
I have a problem when once logged in with the Azure user I am redirected to the Fortinet captive portal -> https://portal.mydomain.com:1003/saml/login, I get the following error in the browser:
Your connection is not private NET:ERR_AUTHORITY_INVALID

I have a wildcard certificate installed in the forti *.mydomain.com
Under "User & Authentication" -> Authentication Settings I have FQDN checked and under "Certificate" I have the wildcard certificate.
In protocol settings I have checked all protocols
Authentication Scheme, Captivce portal and HTTP redirect are unchecked (I don't know if they have to be checked).

Under User&Authentication -> Single Sig-ON ->Single Sing-On configuration, I have the option certificate -> MyCertificate Wildcard checked.

In this Forti version I could not apply the following configuration because of the IOS version:
config wireless-controller vap
edit "SAML-WiFi"
set auth-cert "My_WildCard" set auth-cert "My_WildCard" set auth-portal-addr "My_WildCard
set auth-portal-addr "portal.mydomain.com"
end

Could this be the reason for the certificate error when redirecting me to the captive portal website?
How can I fix it?
Thanks

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