Mixcraft uses the VST3 versions of the Sessionwire plugins on Windows.
You can hear Guests inside Mixcraft by putting the Sessionwire Receive plugin on a track whose output goes to an Output Track instead of the Master Track, and setting HQ Audio Destination to the Sessionwire Receive Plugin. Mixcraft can't record that incoming audio, though. The simplest setup is to send from Mixcraft and listen to your Guests outside it, as above. To record remote performers, have them record on their side and send you the files. See Record someone with the Receive plugin.
If the plugins don't work, check you're using the VST3 version, and see Set up Sessionwire on Windows.