The downloads consist of a single PNG file. I think there might be something missing.
Did they upload a screenshot instead of their game?
If you go to the itch page for this game there are some instructions, although I've not tried it myself, I don't know what a PICO-8 is
As this is a PICO-8 game, simply save the png then drag and drop it onto PICO-8 while it's running. Easy peasy!
