Project is setup to use Yarn 2 for package and build. You can choose to use NPM too which is the default mostly.
Read why Yarn 2 makes sense:
https://yarnpkg.com/getting-started/qa#why-should-you-upgrade-to-yarn-modern
https://yarnpkg.com/getting-started/install
If you do not wish to use Yarn 2 then move to section - "Getting Started"
npm install -g yarn
yarn set version berry
yarn set version stable
yarn plugin import interactive-tools
This will help you to update the package in interactive mode using:
yarn upgrade-interactive
This setup is all about how to use webpack setup for development & production.
Please refer to my medium article for complete setup
Thank you,
-Alok