On your solarwinds server when you open up the database manager you should see Add default server.
When you click on this it should add your Orion database into this view.
At that time you should be able to expand to the section above.
User device tracker is a cross product integration and you may not be using it. I should have had you check this first but if you go to the Admin page again under setting in Orion you should see the cross product integration section.
If you have this i can get you what you need hopefully. If not i am not sure how to come by this info. Most of our AD tracking is tracked by Infosec.
Hope this helps