usability - How to force user to select a location and not simply type it?

Let's suppose this simple form:

So, the user is expected to enter the keywords of the meeting's full address.
While typing, suggestions are displayed (autocomplete feature).

Here's an example:

As the user only selects some keywords, in 99% of cases, the user would select the right address in the list.
That's fine, but what about other 1% that would just valid the form without selecting an item in the list, since they might have typed a complete address in one shot.

Why do I expect user to select the address even if he well typed it?
Because when selecting, I have a background process that associates the latitude/longitude with the chosen complete address.

I don't want user to bypass this mapping, otherwise the meeting couldn't be geolocalized.

How should I format the form so that the user understands that a selection is mandatory, in order to associate the latitude/longitude?

I could by default select the first selection (in case where the typed address matched), but there might be some cases where the typed address would not be fully complete, leading to few possible results.

UPDATE------ Actually, the real form is this: (on a mobile device since a native app)

What may you suggest to increase UX (despite the design, not made yet :))? I strictly don't want to let the user clicks on Next before selecting a valid address.

When clicking on the item "New York Times Plaza", the value is put in the input text, in background the latitude/longitude is set, and therefore the user should click on "Next":