The WebBrowser control is stuck in IE7 mode by default, unless you change the registry on every computer which runs your application:
Web Browser Control & Specifying the IE Version - Rick Strahl's Web Log
Google Maps will not work in any version of Internet Explorer prior to IE10. And even then, support for IE10 will be dropped very soon - the plan was originally to drop it by the end of this month, although that may have changed.
If you want to embed a web browser which supports modern sites, you'll need to use something else. For example, CefSharp
] or WebView