You need to install Node.js first. Then, you need to install Yarn using Npm like this:

npm install --global yarn

So, you can use Yarn to install libraries in packages.json like this: yarn install

Then build project:

yarn build

And then run project:

yarn start

NOTE:

If you get an error like this:

C:\Users\Username\clientha>yarn start yarn run v1.16.0 $ export HTTPS=true && react-scripts start 'export' is not recognized as an internal or external command, operable program or batch file. error Command failed with exit code 1. info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

In this case, just try SET instead of Export in package.json like this:

  "start": "set HTTPS=true&& react-scripts start",