Hi there!
OK, I tried again (both in the browser and downloading), and it's no-go, it still fails at the same point. (It did eventually progress pass "reach the stretcher"... But that was long after I'd dropped it off, and while I was wandering round the incinerator room?!?)
I recorded a video so you can see the issue for yourself, hope it helps.
Update: yeah, so I just double-checked and, sure enough, walking around in that specific area of the incinerator room is what progresses the tutorial past the first tooltip (even before you've gotten the stretcher). I guess the very first time I played, I happened to explore and wander there before I'd gone for the stretcher. So it looks like there's a mis-aligned trigger here.