1. U need to install game from .iso file, he can be opened by daemon tools, ultraISO and etc.
2. From 2 folder copy with rewriting all files to ur GH3 installation folder
3. (optionally) For best framerate you need to download 3dAnalyzer and install in ur system folder, open this program and turn on all the ticks as in the setup.png. Save batch file as gh3.bat in GH3 folder. You may create shortcut for gh3.bat.

Download link: https://drive.google.com/drive/folders/1BDaUE4JeYKNH9VFFvzOvCy_LSEztlVbG