Installing the game.

When installing the game, the system (OS) needs to create temporary files on drive C, and after installation, they are no longer needed, freeing up space on drive C.
However, there is another possible scenario: after deleting the game, it remains in the Recycle Bin, and the files of the deleted game still occupy space on the hard drive (even though the game's directory is no longer present)... you need to empty the Recycle Bin.

P.S. Thank you to the moderators for promptly moving the post to the appropriate topic!!!