google_maps_flutter: ^1.0.2
  google_maps_flutter_web: ^0.1.0+3

import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';

void main() async {
  runApp(App());
}

class App extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: AppCore(),
    );
  }
}

class AppCore extends StatefulWidget {
  @override
  _AppCoreState createState() => _AppCoreState();
}
class _AppCoreState extends State<AppCore> {
  
  @override
  Widget build(BuildContext context) {
    return GoogleMap(
      initialCameraPosition: const CameraPosition(target: LatLng(0, 10), zoom: 4),
      markers: [
        Marker(
          markerId: MarkerId('markerId'),
          position: LatLng(0, 10),
          infoWindow: InfoWindow(
            title:'title',
            snippet: 'snippet', // <--- here
          )
        )
      ].toSet(),
    );
  }
}

% flutter doctor -v
[✓] Flutter (Channel master, 1.23.0-8.0.pre.284, on Mac OS X 10.15.7 19H2 x86_64, locale en-CY)
    • Flutter version 1.23.0-8.0.pre.284 at /Users/Sammius/Flutter/flutter
    • Framework revision eefcff900c (10 hours ago), 2020-10-10 23:42:02 +0200
    • Engine revision 11d756a62e
    • Dart version 2.11.0 (build 2.11.0-207.0.dev)

 
[✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    • Android SDK at /Users/Sammius/android
    • Platform android-29, build-tools 28.0.3
    • ANDROID_HOME = /Users/Sammius/android
    • ANDROID_SDK_ROOT = /Users/Sammius/android
    • Java binary at: /Library/Java/JavaVirtualMachines/jdk-10.0.2.jdk/Contents/Home/bin/java
    • Java version Java(TM) SE Runtime Environment 18.3 (build 10.0.2+13)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 12.0.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 12.0.1, Build version 12A7300
    • CocoaPods version 1.10.0.rc.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[!] Android Studio (not installed)
    • Android Studio not found; download from https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup for detailed instructions).

[✓] IntelliJ IDEA Community Edition (version 2019.2.3)
    • IntelliJ at /Applications/IntelliJ IDEA CE.app
    • Flutter plugin version 39.0.5
    • Dart plugin version 192.7402

[✓] VS Code (version 1.50.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.15.0

[✓] Connected device (3 available)
    • iPhone 11 Pro (mobile) • 932ADBE8-AFEE-49F6-BED9-109EC9869A1B • ios            • com.apple.CoreSimulator.SimRuntime.iOS-14-0 (simulator)
    • Web Server (web)       • web-server                           • web-javascript • Flutter Tools
    • Chrome (web)           • chrome                               • web-javascript • Google Chrome 85.0.4183.121

! Doctor found issues in 1 category.