Welcome, dear friends!
The work continued with the laying of the shrouds, according to the following drawing, found in Pino dall'Orco "Sartie, stile mediterraneo" from ARCHITETTURA NAVALE: ANNOTAZIONI E STUDI.

I made four pairs of shrouds:
alternating them at the top:
and then wrapping the whole thing with rope:
Of course, the mast is tapered a bit at the top.
The next steps are quite problematic; regarding the crossbar, there are inconsistencies between drawings and figures in the instructions.
One must consider that one must place the stay, Jakob's ladder, the halyard, and the mainmast lift.
All while leaving room enough for a person to pass through the passage under the top, like in this figure:

“Schlusselfelder Schiff” , 1503.
Instead, from the bronze bas-relief depicting the sacrifice of Jonah (1514) it is clear that the bottom of the top is closed:

Clearly, in the last type of construction, there was an external staircase of wood or rope:

Drawing of H. E. Adametz for his SANTA MARIA.
The Nao of Matarò seems to have the bottom open, given the lighting on the underlying bars:

but it may also be the effect of breakages or failures over the centuries.
See you later!
Rodolfo