If your WHMCS > setup > addon modules is showing a blank page after uploading the WHMCS Template files this generally means your server is running a different version of PHP or Ioncube.
How to find the specific error
To find the specific error go to WHMCS admin > setup > general settings > other > turn on PHP errors
Next load your WHMCS > setup > addon modules page again and you should see a error listed
Send this error to us
Next submit a support ticket below and paste the error in the body of the ticket. We will check the error and send you the files you need for your server settings.