so it like comes in a zip folder u extract it and then u open the extracted folder then you just open the "Scratchin' Melodii - SAGE 2022 Demo" (also labeled as application on the side so you'll prolly know which to open)
you can either play it like that OR you can add it to the library of ur steam before you play it (idk what difference does adding it to steam makes but its cool to add it in)