To get SATs paired to your SUB you need to see the SUB in the app. For this you'll need to make sure the SUB is connected to the same network as your phone. To do so, follow the setup instructions in the app or have a look at the following video:
When you see the SUB in the app, hit the ‘Add a Follower’ button and follow the instructions stated on the popup that appears. When pairing a SAT with a SUB for the first time, always make sure to set the Follower SAT into pairing mode (pulsing pink) before clicking the ‘Accept Follower’ button.
Haven't you updated the firmware of your SAT(s) yet? Make sure they're plugged into a power socket. The initial production firmware (version n002p004) makes the SAT fall asleep too quickly when it's not plugged to power. The latest firmware version does not have this problem anymore. That's why we recommend updating the firmware of your speakers as soon as possible.