Hello, @Oles_Lototsiy.
In the documentation, we talked about running an empty project using Flutter (for example using Android Studio). You just need to create your project and try to run it at Android and iOS. After you have managed to do this. It will become clear that with your settings of the development studio and Flutter, as well as all the necessary tools, everything is in order. After these steps, you can start launching the native-shell in which you will package your application.
We recently released more detailed documentation, but the iOS section and the release details are not yet fully completed. However, the sequence of launching the application for Android is described in detail there.
https://backendless.com/docs/uibuilder/ui_configuring_flutter_shell.html
Regars, Nikita.