Poop deck is the raised deck at the back of the ship. It's also a very old kit, the molds having gone through several owners. The Minicraft people tell me the molds have only been maintained, never updated or corrected. The molds will go to China for maintenance and future production but no fixes of inaccuracies are planned. There are a number of poor fits.
Test fit the superstructure to the hull several times and adjust the tabs on the hull.
Test fit the decks in combination several times. You'll still need filler. Be prepared for much filing and sanding of the mold lines on all the small parts. There are other extra cowl vents of different sizes you end up using in the end game. When the light hits it just right, you can see the glint off the glass and it gives the model some life.