During setup, the Milo mobile app will give you the option of either joining Milo with your existing network, or creating a new network. The first option merges your Milo network with your existing router's network, while the latter option results in the creation of two separate networks.
We typically recommend that you create a new network, because this way you can see whether your device is connected to your router or to Milo at any given time. Your device should automatically choose which network to connect to based on which network has the best signal in any given location. This will allow you to choose which wireless network to connect. This can be extremely helpful when trying to print to a wireless printer that is only accessible from the network that it is connected. In this case, connect your device to the same network as the printer.
But for simplicity's sake, you might want one single, unified network in your home or business. In this case, you would choose to join your existing network. This option gives Milo the same name as your router's network, which combines them into one singular network.
Whichever option you choose, you'll still get the same full benefits of Milo's total coverage enhancement.