To create a new Flutter project containing existing Flutter source code files:
In the IDE, click Create New Project from the Welcome window or File > New > Project from the main IDE window.
Important: Do not use the New > Project from existing sources option for Flutter projects.
Select Flutter in the menu, and click Next.
Under Project location enter, or browse to, the directory holding existing Flutter source code files (from the Zip file you downloaded from CodeCanyon).
The project will be loaded in Android Studio, you will see some alert messages.
From the terminal: Run
flutter pub get. to load all dependencies in project.
Your code now is loaded into Android Studio, you can Edit, Browse, Change, and Use any source code file in the project.
You should to have a good knowledge developing in Flutter to use these widgets and integrate kits inside your app, full reference of Flutter can be found here https://flutter.dev/docs