You need to run the following command in the relevant project folder to generate the platform folders (Android, iOS, Web, etc). Some of the tutorials will have these already included, if needed.
flutter create .
https://pub.dev/publishers/funwith.app/packages
Riverpod 001 - Counter App Three Ways [ Video ] [ Code ] - Learn how, and when, to use ChangeNotifier, ValueNotifier and StateProvider. This in introduction to Riverpod, to get your feet wet.