In general, the game should be able to read the save file in the .h4s format, and the .h4c format is for maps. You can try this: go to Service - Folder Properties - View, and uncheck the box next to "(Hide extensions for registered file types)."
Then rename the file.
Added 5 minutes later
Did you put the file you downloaded into the games folder or the maps folder?
It needs to be in the games folder. Then use it from the "Load Saved Game" menu.
