git clone https://github.com/ysfmag/aws-amplify-react-custom-ui-example.git
cd aws-amplify-react-custom-ui-example
amplify init
amplify add auth
yarn
yarn start
in the file src/index.js you need to uncomment those line
// import awsconfig from "./aws-exports";
// Amplify.configure(awsconfig);
Code Example for usign aws-amplify-react-custom-ui lib
https://stackblitz.com/github/ysfmag/aws-amplify-react-custom-ui-example