what is the file called? if its snapgame.ipk3 you need GZDoom. The latest version is here.
Viewing post in Snap the Sentinel - Episode 1 comments
if it gives you a error try https://github.com/ZDoom/gzdoom/releases/tag/g4.8.2
most likely the error is
Script error, "snapgame.ipk3:cvarinfo.txt" line 1:
cvar 'snap_shortcutscenes' already exists