Nothing- hence why I corrected him to 2019.
Up till Feb 2019 FSD was sold as basically level 5 driving for $3000 (if you bought prior to delivery) but with the understanding it might take a while to deliver it.
To be able to add it you had to first pay $5000 (again pre-delivery) for Enhanced Autopilot.
EAP gave you all the features post-Feb-2019 cars with FSD have today.