Certificate Based Authentication for on Premises Skype for Business

I am having an issue passing a certificate into the Skype for Business Application. 

When I launch the App and login - I properly get directed to my ADFS login. But when I touch on "Sign in using an X.509 certificate" - it redirects to a blank white page and just sits there. 

https://blogs.technet.microsoft.com/enterprisemobility/2016/07/18/azuread-certificate-based-authentication-for-ios-and-android-now-in-preview/ says that I need to install the "Azure Authenticator" app, but I cannot find that in the App Store. This articles comments section also says the: 

"Azure Authenticator provides SSO capabilities which is one of the many benefits of the app. Office applications have the ability to use Azure Authenticator for authentication. To enable certificate authentication, Azure Authenticator has been updated to use the safari viewcontroller which allows it to access the user certificate provisioned in the system keychain. Without it, the certificate can’t be accessed by Office applications."

Two questions: 

1. Where is this app and how can I configure it?

2. Can I use Certificate Based Authentication (with ADAL/Modern Auth) with an on premises Skype for Business server?