Azure AD Saml SSO not working

Your software
My Mautic version is: 5.0.4
My PHP version is: 8.1
My Database type and version is: MariaDB 10.6

Your problem
My problem is:
I configured SAML for Azure AD setup, following this post and the documentation .
First problem is that when I try to upload the mautic.xml file in Configuration > User/Authentication Settings the file disappear and isn’t uploaded

I tried to create the folder saml in docroot and put inside the mautic.xml file but:
second problem, when I test the authentication I receive this error: “Invalid login. Please verify credentials”

How can I solve? Thank you any help