Thanks for clearing this, iacdxb.
Please have a look at the clip below. I just take a few polygons and connect those. Then you might apply some bevels to the connecting edges and extrude with caps, or Cloth, etc.
After that, move some points to fit it to the cube based model. The upper glue strip is perhaps just an extrude.
Screen capture:
https://www.amazon.com/clouddrive/share/Nske5IDkckE57YtHb8BihlD59ixaB6wHWb5q4OmAU3x
I have pushed them further apart then perhaps needed, for demo purposes.
As a side note, I did package design (from start to finish) for three years while staying in Munich with my company, and I loved to take the reference packages apart to have the flat card-board, if I had to update an older design. It often helped to understand the object, in terms of folding and size-logic/dependencies.
All the best
P.S.: I would have loved to see IMG_9006 fully open, deep into the middle or center fold. So I did a little dummy, see image, I hope that resembles yours.