You don’t need to download or install the gaming client. It is completely optional. The only thing necessary is to sign up for a free account. This gaming site is known for its DRM-free store and will not force you to use their client.
Once the game is in your library, click the game and you will see the installers for the gaming client. Click the “More” button just below the game title and select “Classic Installers”. The screen will switch to the links for just the game, Grim Fandango Remastered.
Download the 2 files to the same folder on your computer and then launch the installer from within the folder. You will now start installing JUST the game.