Ok I see. For some reason, launch game option was greyed so I thought it does not work yet. I played a bit with game folders and now is enabled.

Then all ok. I still think the launch game should be the most visible button, something just below "disable" option. Maybe SoD icon is ok for that button.

Game directory: I will play devil advocate. I download something called Ramm, so I had to read again this thread to see if is mod manager. Seeing that size is almost same, figured is mod manager. Checked previous version, they were called mod manager in download.

Then in install phase, it proposes me program files (x86). Maybe some people have the game there, but the latest HoMM3, the gog one, is going in C:\GOG Games. Does not matter much, but wasn't clear for me:
   
1) what I install
2) where to install
3) if the new mod manager has to be installed in Homm folder

Now ok.