No installation necessary.

After downloading upzip file.

Copy Quake (1996) folder to your computer.
Open Quake (1996) folder.

Find the application executable file, darkplaces.
Click on the darkplaces file to start game.

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Create a shortcut to make starting the game easier.

Right mouse click on darkplaces file and Create shortcut.

Then copy Quake 1 (1996) short cut to Desktop.

Click on short cut to play Quake 1 (1996)

You can rename short cut to Quake (1996)

Finish.