Check your emails to see if you have it 
No phone purchase required, you can choose a free sim kit 
Make sure to choose the $65 plan.
New Customers Only [not a customer within the last 6months].
Port-In Required.
Lastly here if you like Google Fi - A Simple, Wireless Phone Plan With Unlimited Data
Actually I have seen data points about this offer not working with referrals so YMMV