It’s not that critical so long as it’s a ‘powered’ hub! Anker 9 port hubs I’ve heard are good, 8 ports are much more common and using 2 8 port hubs will also work, giving you additional free ports, there are also 10 and 12 port hubs, but again, the 8 port are much more readily available. In my own case I have an 8 port powered hub connected to my PC to which the mouse, keyboard and assorted other peripherals are connected. I also have two further 8 port individually powered hubs which are plugged into the first 8 port (i.e. daisy chained) into which all the CMCs are plugged as well as a couple of other periherals. This works for me without ever a problem, I might mention that the hubs are powered before the PC is turned on - just saying…
Remember however that anytime, when updating the firmware etc. the CMC module must be disconnected from any such hub and connected directly to the PCs local port!