I had this problem and found that this year, Google Maps changed their system.
You need to enable "Maps JavaScript API" but you also need to enable "Places API" ( https://console.cloud.google.com/apis/library/places-backend.googleapis.com ) and set up billing with your credit card. Even if you're using the free portion of the api, Google makes you enter a credit card before your map feature will work in Mailwizz.