: If the extraction fails or says "Unexpected end of data," you are likely missing one of the numbered volumes.
You can use 7-Zip on any computer, including a computer in a commercial organization. You don't need to register or pay for 7-Zip. How to Extract .7z.001 files - Microsoft Q&A
: Select "Extract Here" or "Extract to [Folder Name]" from the context menu. The software will automatically detect and join the subsequent parts to reconstruct the original file. Troubleshooting