Hi-
Please make sure the plug-in is activated in the iLok License Manager. You also need to confirm that you have the proper VST path set in your REAPER vst preferences.
If you are using 32-bit REAPER, the path is: C:Program Files (x86)Common FilesSteinbergVST2
If you are using 64-bit REAPER, the path is: C:Program FilesCommon FilesSteinbergVST2
Let me know if the issue persists. Note that we only support Windows 7 and higher.
-Tom