How do I redeem Netflix on us if I have an existing Netflix account

I followed the following simple process. It took less than 10 min for me to complete.

1. Call T-Mobile customer care (611)
2. Check if you are eligible for “Netflix on us”
3. If yes, request activation through text message
4. You will receive a text message with a link to activate.
5. Open the link with your T-Mobile mobile app.
6. It will ask you choose from the options(may be different for other). I choose "Netflix Premium for $10" coz that's my existing plan.
7. Once setup, app will take you to a Netflix page, where you can either create a new subscription or use your existing account id(email) to link it your T-Mobile account. I did the later.
8. You are all set. Netflix will stop billing($17.99) and T-Mobile will start($10) and you save $8/month.