Firstly, I love Lutris. It’s a great front end for configuring Wine prefixes for installing games. It provides the runtimes you’ll need and settings to choose/enable/disable them etc.
However, those game installation scripts are bollocks! Unless someone is going to like test and maintain them every week, they are going to cause a lot of waaambulance calls.
My advice is to just learn how to use Lutris to manually configure a game’s Wine prefix and then simply run the downloaded GoG installers.
In this case, the problem you are running into is likely that the scripts are going to download the games through GoG Galaxy. I’m like you, I would NEVER want a stupid, unnecessary game client program for GoG games. That’s the whole reason I buy them there, I’d actually prefer Steam if I had to do it that way.
To get you started, in Lutris, click the + sign to add a new game. Choose “Locally installed game” (even though the game is not installed yet). Go through the tabs and supply the relevant info.
On the first tab, Game Info, all you need to do is give it a name and choose the runner, which is “Wine (runs Windows games)”
On the second tab, Game Options, leave the Executable field blank for now (you’ll fill it in after you get the game installed with the path to the game executable). You must specify the Wine prefix here though, the path to where you want it to be. Use absolute unix paths here, like /home/yourname/games/whatever
On the third tab, Runner Options, enable Advanced View so you can actually see all the fields (though most of them you won’t have to touch). Now, you must choose your Wine version from the drop list. Enable DXVK and VKD3D if not enabled. The latest versions will probably be the defaults.
Save the settings.
Now, in Lutris, click on the new tile and first, in the right hand drop list, the one with the wine glass icon, choose “Run EXE inside Wine prefix” and browse for your GoG installer exe.
After your game is installed, go back to the Game’s Settings in Lutris (in the left hand drop list beside the Play button, go to “Configure”) and on the Game Options tab, here is where you must now specify the path to the game Executable to play it.
I hope this is enough to get you started. Get onto this and you’ll have the freedom to get your games working how you want them to.
There’s more advanced shit like using Winetricks to install various Windows runtimes etc. into the wine prefix, but most of the time it’s not necessary.