So I decided to give this mod a go. I started as the Portuguese. There's quite a few issues. For starters, the assassins seem like they would train your armies, due to the training tree being available, but they can't actually train anything. So it's a waste to use that part of the tree. The spies abilities of setting up a network (comes with a new spy) don't work either.

But that's not too problematic, you can still use them in different ways. Problematic is the fact that you can't hire "Cavaleiros Apeados" or the Portuguese melee infantry. I built a fort city in Portucalense and upgraded it to the point where the recruitment becomes available and tried to recruit this unit, but it was greyed out. I figured maybe it was a cap, like the spanish order foot knights, so I tried using a submod that removes caps and still you can't hire them. Their unit card won't even show up when you hover over them.

Given that you're severely handicapped without heavy infantry, the Portuguese campaign is effectively bricked.

As a side note, "Spanish knights" is a terribly innacurate name for the Iberian crusader orders. You had several historical orders, like order Avis, Calatrava and Santiago, but the word "Spanish" was only created much later, around the 1500s with the creation of Spain. The concept of Spain didn't exist before, since the modern day Spain was spread out over multiple different kingdoms.