Sorry to hear you are having issues. Try this,
Press the Windows key and "R" at the same time. A "Run" dialog box will pop up, please paste the path below into the "Open" field and press OK.
In the folder that pops up, you should see a folder named PRODUCTNAME. Please delete this folder and all of its contents.
After you have deleted that folder, please attempt to activate once again and it should succeed without any errors.
Please let me know if this does not resolve the issue.
Stardock Community Assistant