SSO users of XpressDox do not have to see the login screen at all
Once your XpressDox account is configured to use SSO, there is no need to present this screen to users and risk them entering credentials. Or even have them click the “Sign in or Register with Microsoft” button.
Rather give them a new shortcut URL to access the XpressDox Explorer:
https://<yourXpressDoxInstance>/Sso/Start?type=Microsoft