I used Homebrew to install Node. Before starting, I like to run the following commands...

Homebrew Commands:

brew update
brew upgrade

Check which version of Node and NPM you are running:

node -v
npm -v

Initialize a React App:

npx create-react-app frontend
or
npm init react-app ./frontend

Initialize the Node backend:

mkdir backend
cd backend
npm init -y

frontend folder needs this package installed:

npm install react-router-dom

backend folder needs these packages installed:

npm install --save-dev nodemon
npm install express body-parser concurrently

Update the frontend/package.json with the "proxy" code:

"proxy": "http://localhost:4000/",

See the package.json file for npm run scripts.