I've been trying to get HOI III installed since yesterday when I bought it, and it hasn't worked so far.
Process is as follows:
I click the button "Install"
The game downloads (to 100%)
The game gets moved (also to 100%)
The installation fails.
Hard drive access error/failure.
I dont have any other reports of that happening and repairing the installation does not work. The procedure only starts at the top.
In another topic there was a solution where they should try disabling their Antivirus, and I did that too, nothing changed. Plus with Kaspersky, it's always a bit tricky to find what you want...

EDIT: Just an hour earlier, I managed to install two other games without incident, so I honestly doubt that it has to do with the Antivirus but hell, I dunno...

I hope someone has a solution for my problem

Same problem here. I can install the game neither from GOG Galaxy nor from the downloaded backup files.

same problem

Win 10 Home 64 bit

Thanks alot dude, this solved it for me :)

Thanks for the info had the same problem using win 10 pro galaxy gave up after it had installed hoi3 and said there was a hard disc fault. Tried the advice here and got hoi3 running. Surely GOG should have got galaxt working better than this by now

If nobody reports a problem then it never gets fixed.