Question about Arctic Z3 Pro with USB 3.0 hub

Yes
Only the one in the middle is height-adjustable, and only if the stand is supplied with a height-adjustable suspension. If this is not the case, as it was for me, simply contact Arctic Support and ask for the height-adjustable suspension. The part was delivered to me immediately and free of charge, including a replacement part for the cable cover, which I had broken when setting up the stand.
I can definitely recommend the stand.

The "arms" are simply very long (-> up to 30" possible). I also have 3x 24" screens on it and had to shorten the arms with a saw because otherwise the arms would have extended too far back and I would have had to place the desk far away from the wall. But basically recommendable!