Hi soko22,
Sorry to hear you're having trouble! It looks like you might be missing some parts of the archive.
You need all 9 files present to extract successfully (DesktopGarageKit18.zip + .z01 to .z08). Please ensure you have all of them in a folder with a pure English path.
Once you have all 9, right-click the .zip file via WinRAR to extract. If you still get errors, a file might be corrupted, so please try downloading them again. Feel free to reply if you're still stuck!
warm regards,
1UP