I have installed 'evolution-ews' package and need some information for configuring mail account.

I tried it in following way:
I selected 'Exchange Web Services' as server type, Host URL: https://mail."mycompanyname".com (In general I access my mails through this URL).
OAB URL: Nothing.

When click on 'Fetch URL' , it's throwing 'Autodiscover failed: Code: 401 - Unexpected response from server' error.

Can anyone tell what should I give host URL and OAB URL?