Diablo III: Eternal Collection is not officially available as a free download. While some third-party sites claim to offer "free downloads" of the full game, these are often pirated "repacks" or ROMs for emulators that may pose security risks or violate terms of service.
If you want to play Diablo III for free or at a lower cost legally, here are the official options: Diablo III: Eternal Collection Free Download (v...
You can access the full game through certain subscription services rather than buying it outright: Diablo III: Eternal Collection is not officially available