This upgrade package is only for users who had purchased 'Paid Customer Groups' and still has an access to the latest version of that extension. If you do not have the access to latest version of 'Paid Customer Groups' (with an upgrade key), do not buy this item, it will not work for you. Instead, you should buy a full version of 'Paid Customer Groups for Opencart 2' at this URL:

http://www.opencart.com/index.php?route=extension/extension/info&extension_id=22579

The 'Paid Customer Groups' extension for Opencart 1.5.x versions is available here:

http://www.opencart.com/index.php?route=extension/extension/info&extension_id=5348

If you have any questions or notes regarding the upgrade procedure please post it in comments, I will reply you directly at your email.