Pro Sites: don't know how to add domain mapping on prosites

i install the prosite and domain mapping after, i go to prosite module gateway and premium plugin is didnt see and domain mapping plugin is showing.

i have free level and 4 pro level here, i hope to have permission on 3rd and 4th level can access domain mapping only.

now my domain mapping and prosite plugin is do Separate job.
can guide me to install or setting correctly?