Android SDK does not launch when launching a React Native project on macOS. what am i doing wrong?

Question

React Native

BUILD FAILED in 1s error
Could not install the app on the device, read the error above for details.
Make sure you have an Android emulator running or a device connected and have
set up your Android development environment:
https://facebook.github.io/react-native/docs/getti...
error Command failed: ./gradlew app: installDebug. Run CLI with --verbose flag for more details.
on Add the following lines to your $HOME/.bash_profile config file: shows that there is no command.