Error code 18 can occur when the installed software does not have the correct permissions to write a required file. To resolve this, please try running the app on your PC as an administrator.
To do this please firstly close the App if it is open. Right click on the App icon either on your desktop or in your programs folder. Select 'Properties' and then go to the 'Compatibility' tab. On here please select to 'Run this program as an administrator'. Once done press 'Apply' and then 'OK'.
Please then re-launch the app and try again. The should now activate successfully.