I work with files every day, and I'm not sure I would have realised I'd needed to save manually with the original MapHub UI either. A web-based interface that looks like that, I expect it to be transparent. If it'd had three icons (the classic blank page, open folder and floppy disk) in the top left, then I'd assume it would need manual saving. (I'm not saying that's what you need to do, just analysing my own intuitions)
The interesting bit is that for years this wasn't a problem. Like for 5 years I got 0 support requests about missing Save. Also web apps were not auto-saving traditionally, many of them still don't do it today.
It's very possible that if you showed me the MapHub UI eight years ago, I'd have intuited that I'd need to save manually---I can't tell for sure. I am definitely aware that the way I engage with software nowadays is very different than when I started using computers in the early 2000s, and I don't doubt it is still evolving due to the changing conventions in UI and functionality.
