Since there isn't one official "zip" for this, users typically use (the original L4D prototype found in CS 1.6) or community skin packs:
Open CS16Client, select the path to your xash folder, and launch the game. README.txt - Stabbath/ProMod - GitHub
Install both the Xash3D FWGS and CS16Client APKs on your device.
Copy the valve and cstrike folders from your PC's Steam installation of Counter-Strike 1.6 into the xash folder on your phone.
Many players use the "Zombie Plague" or "Zombie Scenario" mods which emulate the L4D experience. 3. Installation Guide (Readme)