How to integrate subscribe by email with Comments Plus ?

Hello,

On https://premium.wpmudev.org/project/comments-plus/, it says "Fully integrated with subscribe by email with Facebook and Google".
I've searched for 15 minutes but I can't find how to integrate subscribe by email with Comments Plus ? I don't see any option to activate it (it's not activated > ex: http://renega.wpengine.com/2012/06/14/hello-world/ ).

Thank you very much for your help