As a legacy title, it is sometimes hosted on the Internet Archive for historical preservation. Quick System Requirements (Classic DF1)
If you are looking for the "full version" of the classic game, it is widely considered or available through digital storefronts for a small fee: download-delta-force-1-game-for-pc-full-version-free
The latest version is a tactical shooter. It includes operator-based extraction modes and large-scale 32v32 warfare. As a legacy title, it is sometimes hosted