Why is Whatsapp not adding my Outlook contacts to favorites?

[Windows Central Question]

why whatsapp is not adding my outlook contacts to favorites

in my lumia 625 whatsapp is not adding my outlook contacts to favorites. the add new chat (+) and call options are not working. somebody help me with this

 

[grantpwarren]

Whatsapp relies on you phone contacts only, that are saved to your phone, sync outlook to your phone then it'll show phone number contacts.

 

[div3rsion]

How do i sync them to my phone.
My outlook contacts are there automatically when connected to my ms-account.
I don't know any other way of storing contacts.