Oh, so it's Godot! Use "Export Project" not "PCK/ZIP".
Always try html5 first - need to use GLES2 renderer (top-right corner you can switch) - if you want to make html5 and mobile games you need to use it. Drawback is that you have to use CPUparticles instead of ordinary and few small things you can learn by making html5 jam games and testing in browser. For html you need to name export index.html and ZIP all 5 files, then submit as html instead as downloadable.
For windows just use "Export project".