flutter doctor

This command checks your environment and displays a report to the terminal
window. The Dart SDK is bundled with Flutter; it is not necessary to install
Dart separately. Check the output carefully for other software you might
need to install or further tasks to perform (shown in bold text).

For example:

The following sections describe how to perform these tasks and finish the setup
process.

Once you have installed any missing dependencies, run the flutter doctor
command again to verify that you’ve set everything up correctly.

Warning:
  The Flutter tool may occasionally download resources from Google servers.
  By downloading or using the Flutter SDK you agree to the Google Terms of Service.