you can fix the screens as you wish (height). As others have written, the important thing is to balance the weights well so as not to unbalance the whole thing, especially if the screens are changed angle from time to time

the brackets can be fixed all the way down

I have never assembled the bracket and will put it up for sale in t.u.t.t.i

The brackets can be attached as low as you like. However, it is important that the centre of gravity is in the middle, otherwise the part will tip over. You have to pay attention to this when setting it up. I no longer need mine as I have replaced my screens with a large panoramic screen.