Use software like The Unarchiver to handle multi-part 7z archives.
A .7z.001 file indicates that a larger archive (likely a folder, game, or software named "Alissa") has been broken into smaller pieces—starting with .001 , .002 , and so on—to make downloading or storing it easier. Alissa.7z.001
(e.g., .002, .003) in the same folder?
This article explains what these files are and how to properly extract them. What is a .7z.001 File? Use software like The Unarchiver to handle multi-part