When you "bake" the effect from the editor, it doesn't render it out to a spritesheet, it optimizes and packages to make it suitable for realtime playback in a game engine. Some plugins handle the baking step internally and do not require an explicit bake from the editor, such as the UE4 plugin.
In version 1 of popcorn we had a feature that could spit-out rendered frames from the editor, but that's not available for version 2 yet. And it wasn't very well suited to generate spritesheets either.
So the actual workflow is:
- Create your effects in the popcorn editor
- Play them back in a game engine that has a PopcornFX plugin
It uses a different simulation system than Unity's shuriken | VFX graph, or Unreal's cascade | niagara, that's why you need a plugin to play them.
It is not really designed for offline renders