7-Zip will automatically recognize the numbered sequence, join the parts, and extract the files. Troubleshooting Common Issues
This article explains what these files are and how to properly extract them. What is a .7z.001 File? Alissa.7z.001
(e.g., .002, .003) in the same folder?
This happens if you are missing subsequent parts (002, 003, etc.) or if one of the parts is corrupted. join the parts
If you only have Alissa.7z.001 and no other parts, the download is likely incomplete, and the file cannot be opened. To help you further, could you tell me: the download is likely incomplete
With these details, I can tell you exactly how to get your files. How to Extract .7z.001 files - Microsoft Q&A