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 7z archives. Alissa.7z.001
Ensure all parts are in the exact same folder and have the correct names before the .7z.001 extension. This article explains what these files are and
With these details, I can tell you exactly how to get your files. How to Extract .7z.001 files - Microsoft Q&A Alissa.7z.001
Understanding Alissa.7z.001: A Guide to Opening Split 7-Zip Files