Cannot Map a Domain with Domain Mapping Plugin

Morning/Evening All.

I have Domain Mapping plugin installed and activated on a new multisite setup (for folders not sub-domains).
I have pointed the new domains' DNS records to my IP address.
I have created the new site and it can be accessed fine externally at the (http://networkdomain.com/newsitefolder/).

But, when I go to the Domain Mapping option under Tools - I cannot see where to map a domain. Screenshot attached. Help & pointers appreciated.

Thanks.