I think, it is issue of installer.
After installing with error message you must go to your folder C:\ Program Data\...where installer at the time of the download saved the big .zip archive and unzip it to some folder.
You will see the unzipped folder - GTN_Trainer_disc_contents. In this folder activate the autorun and the Trainer & GTN Database will be installed on the disc C.
Then repeat the installation with main installer.
It must work.