Steam key is actually in the "Download" button way at the top:

I found out today that starting a game with all players on the same team immediately triggers a win that counts for probably every applicable "Win a game" achievement. I already got some beforehand so I can't confirm if it works for all of them, but this exploit(?) earned me Nudist Run, Speedrunner, Any% PB and No time to waste.

Is there a way to replay the tutorial?