I find this comment funny in the description part of this item "Nour hookahs have become quite popular due to their designs but most notably for their level of quality." I guess in your instance this isnt true hehe. It does say in the description that it is a solid shaft so it more than likely does not unscrew. You may have to contact them for a replacement tray that actually fits.
The greatest obstacle to discovery isn't ignorance, but the illusion of knowledge