Hello Salvatore,
Thank you for your message.
Please note that the version 6 was discontinued for free license users - in order to use Remote Utilities with a free license, you need to update your installation to version 7. Here's a
guide on how to update Remote Utilities (or you can also just re-install the latest version of the software).
After updating, you can register your Viewer as described
here.
Hope that helps.