You are trying to install Rapid Recovery either the Trial version or the licensed one. You download either the web installer OR the full installer. You run the installer either for a new installation or for an upgrade.
When the installation finishes, the license key which is built into the core name is not applied and you get an error message stating that the license cannot be applied.
In some rare cases the installation may fail as well.
The issue is caused by the way some browsers or environments interpret the name of the Rapid Recovery Core installer with built in license. In certain conditions (i.e. using Firefox to download the trial), the name of the Core installer file may be modified at download time. Specifically, the “=” sign in the installer name is replaced by "%3D" (which is the html code for "=").
If this happens the license is not applied correctly or the installation may even fail. The same issue occurs with the fully licensed version.
To solve the issue, replace the "%3D" code with "=" (no double quotes) in the installer name.