Now that you have a user account, you must register your device to that user account. A device can be registered to only one user account at a time.

To Register a device:

 Go to My Devices tab in App
Make sure your Purpl PRO is powered on. Both LEDs flash Blue when powering on. The Bluetooth LED will flash red every 3-5 seconds if successfully on and connected.

To Register the device, tap the "Register" button on the right box of the serial number. 

You do not need to manually type the serial number in app to register the device. If it is successfully connected via bluetooth to your phone, the serial number will automatically populate. 

If you do not see the SN listed under my devices, click the refresh button at the bottom. If that still doesn't do the trick, swipe up/out and refresh the app and reload it. 

If that fails as well, reboot your phone's bluetooth and give the device a reset as well.
Activate the device for measurement by tapping the toggle switch to the left of the device serial number to set parameters. 
If this is your first time using the device, you will be prompted to Calibrate your Purpl PRO. Please see the next on how to calibrate. You'll need to calibrate the device once a week.