Hey sroper90, thanks for the feedback! And yes, I agree the module is quite packed. It was designed as a 5 room dungeon as an exercise in setting limits on my writing (which I'm evidently struggling with) so the rooms got a bit bloated. My bad!
But to answer your question, the map with the "extra doorway" was intended as an alternative in case GMs wanted to expand on the dungeon themselves or lead it into a new dungeon below.
As of yet, there's no plan to expand on this dungeon, but I'm currently writing a "norse mythology" themed adventure site module that's coming soon, so stay tuned!
I'd love to hear how your session goes afterwards! 😊