It's all good. We were all at this point at some point (I certainly was not that long ago). The reason we need the switch is so that we can connect to all these devices at once from all the devices, including the driver station. Like if you have multiple ports at the back of a WiFi router, that's what this does. It extends the same network to physical devices. With this, you can connect to the Pi directly from either the Driver Station or the Rio. If you want a more detailed explanation, GRIP has a
wonderful tutorial on how to get their very easy to use vision processing up and running on an rPi 2 and get everything set up. The same steps should apply to an rPi 3.