The setup guide that comes with every smart-home device generally directs you to download the companion app as the first step.
The setup guide that comes with every smart-home device generally directs you to download the companion app as the first step. You may have to scan a QR code or enter a serial number, so make sure you run through this process before you mount anything in place or throw anything away, as these codes often appear on the back or underside of devices or the instruction booklet.