Sorry about the loud sfx!
The map layout might be a little confusing, especially with chosen camera angles. Basically, you need to enter this large hall:
and proceed to its far end, where there's two ladders on each side leading to the second floor. Don't ascend the ladders, proceed further to the end of the hall, there would be a room and a music cue would play. From there on you should be able to proceed further.
Hope this helps, and thank you for such positive feedback!
I will be sure to play The Sands of Betrayal.