Hi. My guess is that it installed by default to program files/Steinberg/Vstplugins. Browse to this folder to see if that is the case. If so: When SONAR is open, go to Preferences (P), File, Vst Settings, and add (red) the above folder to SONAR's scan folder. Or if you have your vst scan set to manual, you might have to do a scan, for SONAR to be able to see it (blue)
Hope it helps.
All the best.