In the world of Quake modding and preservation, a .zip file of this nature usually serves one of two purposes:

: Features cross-platform play, dedicated server support for matchmaking, and 4-player local split-screen co-op or deathmatch.

: Support for widescreen and 4K resolutions, enhanced character models, dynamic shadows, and improved lighting.

: Storing the .pak files (such as pak0.pak and pak1.pak ) that contain the game's maps, sounds, and textures in a compressed format that modern engines can often read directly or after extraction. Quake Release Notes & FAQ - Bethesda.net