The second message suggests that Google API key entered by you is no longer valid. It was valid at one point, not anymore. Please generate new Google API key as described in this doc - https://pdn.pega.com/using-address-map-control and configure DSS with new key.
Before configuring the API key, I got the message "This page was unable to display a Google Maps element" which is because that no API is configured in Pega DSS. The API key which I generated is 2 days old and after configuring I see this new message.
"Oops! Something went wrong."
One more point here is while viewing the preview of the section the map is shown/visible for a sec and then getting vanished followed by that error message. If it is the problem with API key configured even the 1 second display should not work. not sure but trying to nail down options.
You need not choose any platform when generating API key. In your Google Code console, go to Credentials->Create Crednetials-> API key -> Select 'Browser' key. That should do it. Is your console showing key Type as Browser?
If you want to add localhost as a referrer - just add localhost/* in the list of referrers.
2. I don't see any type in the console browser vs server etc...
3. I did tried with and without adding localhost/* but no luck and error remains the same like I mentioned in point1
4. the google error list says below . Not sure when the project is existing it is not recognizing and encountering the below issue. I tried creating 3 different projects and new browser API key