Black Button on door handle

Yes it is to lock doors only.

Ok that is what the manual says. I must be doing something wrong.

You might have the passive system disengaged. Check your settings in the infotainment.

Under settings doors and locks?

Depending on year they had a Recall on the Door Handles my 2011 had it on both door handles. Other wise unless you changed settings if you get out of the car and push the button the door locks and you should hear it.

Did not have the setting passive entry clicked

Button won't work if you forget the key fob in the car. Keeps you from locking yourself out.

It appears to use the same near field detection technology as the automatic door unlock. The key has to be in my possession for the button to actually lock the car.