The Echo Plus has a hub built in. That's what all of your light bulbs connect to. Without the hub, none of your light bulbs will work. That said, your Echo Plus should be in a central location, preferably near the center of your house.
The Echo Dot, Spot, and Show 8 do not have a hub built in. Your Hue lights probably came with a hub if you bought it as a kit. The Philips hub is better than what's built in to the Echo Plus. If you have the Philips hub, you should use it.