"USB Needs more power." - Mac Pro with 7 Keyboards?
This kind of applies to all hardware, not just apple computers. I did a search for Anker USB Hub. None of the results showed a powered USB Hub. They all relied on the USB Bus for power. 

The average USB port has about 500 mA available. (900 mA in USB3.0) USB Keyboard uses between 50 mA and 100 mA. The USB hub itself also needs power, more if it's got all those pretty LED's on it. This puts the load between 400 mA (idle?) and 800 mA (all in use?)

So, it seems like your using more power than a single USB port can provide. You may just need to upgrade to a hub that supplies it's own power to devices. Which would require a hub with an AC adaptor.