Into a 625 KB file? UnityPlayer.dll alone should have 19.1 MB. Whatever happened when you extracted the game, the files did not merge on their own.
Try to download and look at another Unity game and compare what happens when you extract it. In the example I’ve linked there should be 2 .exe files, one UnityPlayer.dll and 2 additional folders.
Sorry, I didn’t notice your post earlier. I tried downloading it and everything was there: Unity & the Crash handler, as well as 2 folders.
I can’t identify the issue, but it seems to be on your end. Without watching the process on your end all I can do is guess… Either you only extracted one file by a miss-click (marking all the files and pulling them over, accidentally letting go of the button momentarily, resulting in only one file being dragged). Or maybe your virus scanner got an update based on the whole opt-out telemetry issue with Unity - would be a bit late for that, though…
Maybe try downloading the game from itch.io again and decompress via the right mouse button?
Edit: Also important for diagnosis (by me or others): Does extracting the game I linked work for you?
