I've created an ADAL plugin for Xamarin on top of the Microsoft ADAL plugin.
With this plugin you can add the authetication to your apps with a single line of code.
This is the nuget package: https://www.nuget.org/packages/MarcTron.ADAL/
and you can find a tutorial here: http://www.xamarinexpert.it/2018/03/01/adal-made-easy/
If you have any questions or problems ask me.