Sophos AD/SSo authentication issue

After changing the authentication mechanism to AD sso Kerberos authentication. The client machines are getting additional popup for the browser authentication, so that internet traffic will be allowed.

We have tried by adding the hostname in internet security settings and added in the local intranet and customlevel to use the allow authentication automatically. Even after that it was askinig for the additional authentication in client machine after system login. Kindly let us know anyone facing the same issues. Any help will be appreciable.