Download and install the Fitbit app from the App Store
Open the Fitbit app on your iPhone
Sign in to your Fitbit account or create one
Turn on Bluetooth on your iPhone
Make sure your Fitbit device is charged and nearby
In the Fitbit app, tap your profile picture or account icon
Tap Set Up a Device
Select your Fitbit model
Follow the on-screen instructions
Allow Bluetooth pairing when prompted
Enter any pairing code if requested
Keep the Fitbit app open until setup is complete
Sync your Fitbit by opening the app whenever needed