In the terminal, run the flutter devices command to verify that
Flutter recognizes your connected Android device.  By default,
Flutter uses the version of the Android SDK where your adb
tool is based. If you want Flutter to use a different installation
of the Android SDK, you must set the ANDROID_SDK_ROOT environment
variable to that installation directory.

Set up the Android emulator

To prepare to run and test your Flutter app on the Android emulator,
follow these steps:

Enable
VM acceleration
on your machine.

Launch Android Studio, click the AVD Manager
icon, and select Create Virtual Device…
    
      In older versions of Android Studio, you should instead
launch Android Studio > Tools > Android > AVD Manager and select
Create Virtual Device…. (The Android submenu is only present
when inside an Android project.)
      If you do not have a project open, you can choose 
Configure > AVD Manager and select Create Virtual Device…

Choose a device definition and select Next.