How to implement and configure Single Sign On for ArcGIS Portal using multiple authentication

[JohanaWong]

Hi, my company would like to implement and configure Single Sign On for for ArcGIS Portal using multiple authentication:

1. Gmail 
2. Office 365

   3.  Portal built-in login (user name and password)

From what I understand, I need to configure multiple Web Adaptors. However, its very tricky for me. The portal is hosted on Azure cloud. Pls help. 

Thanks,

Johana