It only states "CAUTION Make sure you enabled the Geocoding API to make the autocomplete feature work!"
I just set up a new site and went to the docs for reference, and could not get it to work. In my case, Geocoding API is not required, but the console pointed me in the right direction, and the Places API is required for autocomplete to work.
So, for future reference, here are the APIs needed :
- Places API