You can activate your TNG RFID Tag following the below steps:
Step 1 : Tap on Toll icon from the home screen and then choose RFID
Step 2 : Click on the Activate RFID Tag button
Step 3 : Fill up your account details
Step 4 : Register your vehicle
Step 5 : Enter the 24-digit RFID Tag number or scan the bar code on the TNG RFID Tag packaging
Step 6 : Enter OTP code
Watch video on RFID tag buy, fit and use here