Yes, you can use Plume with your existing router. Download the app and follow the instructions to set up Plume with your existing router.
Please make sure to turn off the Wi-Fi on your router after the setup to allow Plume to efficiently manage your home Wi-Fi.
Please note that Plume will not work as an extender of your existing Wi-Fi network. Setting up Plume requires you to set up a new Wi-Fi network.