You need install Node, the React Native command line interface and Jdk and Android Studio to build android application.
- Install Choco Choco
Open an Administrator Command Prompt (right click Command Prompt and select “Run as Administrator”), run the following command after install Choco:
choco install -y nodejs.install python2 jdk8
npm install -g react-native-cli
Install Android Studio Download and install Android Studio
More infomation about install and buid ios, android app Getting started with react-native