The file is ok, I have tried to extract with WinRAR and 7zip and it worked fine
You can try WinRAR instead
I getting this error "Unsupported compression file gmapsupp.img" with every 7zip (x32 and x64 versions).
Not long ago using WinRAR, and I do not recommend it to anyone pollution, namely the windows freezes when WinRAR to extract the files.
But I managed to unzip the file in Windows Explorer.
Works great on my zumo 550!Thanks!!!!!