If you are looking for a guaranteed safe and official experience, Valve has transitioned the main series to a free-to-play model:
: The primary hub for CS 1.6 skins, maps, and mod packs. counter-strike-carbon-free-download-pc-game-full-version
While there is no single official website for this specific mod, it is typically hosted on community software and modding platforms. You can look for "full version" downloads on sites like: If you are looking for a guaranteed safe