Either the .pck file is missing, or my exporter to your OS (Probably windows) failed. If it's web... then I don't know what to tell you. This is an old project that's being going for...almost 6 years on three different game engines. (Blender,Godot2.4,Godot3.1) Your best bet is to download Godot3.1 and the source off of gitgud. And play it through the editor itself.
Sorry for the late post, I don't log on here often.