Google Maps on Classic Template

Do you have any advice for how to update the Google Maps in the Classic Template please?
At the moment there is an error that states “This page can’t load Google Maps correctly.” and the image shows ‘for development purposes only’.
I’ve found the maps.js file and edited the latitude and longitude however this doesn’t seem to have made a difference.
Many thanks,

Hi there

“for development purposes only” - You have t provide Google maps api key in the file, without the KEY map will not work