You must specifically right-click on the first file ( .001 ) and select "Extract" or "Open archive" using the 7-Zip GUI.
If the file was downloaded with a slightly different name (e.g., GGIW.7z (2).002 ), it will break the sequence. You must rename it to match the exact prefix of part .001 for the extraction to work. GGIW.7z.002
Ensure you have GGIW.7z.001 , GGIW.7z.002 , and any subsequent parts. You must specifically right-click on the first file (