Compressed installers from unofficial sources are frequently flagged as trojans or contain malware such as crypto-miners.
To reach these sizes, "repackers" often strip away high-quality audio, cutscenes (movies), and even entire levels. Mafia II Highly Compressed PC Game
If you have a low-end PC, the "Classic" version is 5x smaller and often runs more smoothly than the Definitive Edition remaster. "repackers" often strip away high-quality audio
If a download is corrupt, use the Verify Integrity of Game Files tool in Steam settings rather than re-downloading from unverified sources. Mafia II Highly Compressed PC Game