OK thanks, that was it. I made sure all the files .7z.001 to .7z.005 were in the same folder then unzipped the .7z.001 file using 7-Zip and all 5 unzi ...
I was trying to download the artwork packs here (https://www.progettosnaps.net/artworks/) and the zip files for Full 0.202 through Upd 0.217 unzip fin ...