The Atrox functions as a standard Xbox controller. In order to have it recognised by Windows, I expect you'll need to have the Xbox (One) controller drivers installed and present on your system. Download them from here:
http://mjr.mn/XboxOnePCDriversx64Once installed, then follow Razor's instructions if it is not recognised automatically:
1. Click on your Windows icon in the lower left corner, then Right click on Computer
2. Go to Properties
3. Click on Device Manager
4. Double click on the Unidentified Device that should be highlighted in the list by a yellow icon
5. Select "driver" and click on Update Driver
6. Browse my computer for driver software
7. Let me pick from a list of device drivers on my computer
8. Windows Common Controller for Window Class
9. Xbox 360 Controller for Windows
10. Update Driver Warning
11. Click Yes