Because this is a multi-part archive, you cannot open part .004 on its own. Follow these steps to access the guide:
Do you have of the archive, or are you still looking for the first few files ? a1029.7z.004
If you are missing part .001, .002, or .003, you will likely get an error saying the archive is corrupted or the "file is not a supported archive". Because this is a multi-part archive, you cannot open part
7-Zip will automatically recognize that parts .002 through .004 are present and combine them into the original full file. Troubleshooting 7-Zip will automatically recognize that parts
The file is the fourth part of a split (multi-volume) 7-Zip archive . To use this "solid guide," you must have all the preceding parts (001, 002, and 003) in the same folder to successfully extract the full content. How to Extract Your Guide
Ensure you have a1029.7z.001 , a1029.7z.002 , a1029.7z.003 , and your current a1029.7z.004 in the same directory.