Just realized, our car already has a fastag, it came pre applied when we bought the car in June 2019. It is already linked to paytm and pre loaded with 200 rupees balance, 150 in fastag toll wallet and 50 in paytm wallet.
If you have insufficient balance in your paytm wallet, it'll be debited from your fastag wallet.
It is recommended you always keep 150 in your fastag wallet.
We drive through the fastag lane, and the process is fully automatic.