You rarely find large games (which can be 50GB+) as a single download. Uploaders split them into "parts" (part01, part02, etc.) for several reasons:
This identifies the content. It refers to the fourth major wave of post-launch content for Bandai Namco’s hit fighting game, which included characters like Kunimitsu and Lidia Sobieska.
Multi-part archives allow users to download different segments simultaneously from different mirrors. 3. How These Files Work
Pirated copies cannot access official online multiplayer—the core of the Tekken experience—and do not receive automatic balance patches or updates.