gi clone https://github.com/AxelReid/mern-full-stack-app.git --recurse
install dependencies of the root
npm install
and
install dependencies of the front-end
// cd ./frontend
npm install
then you need to create a .env file and fill it with
DB_CONNECT=<mongodb_uri>
TOKEN_SECRET=<a_random_long_string>
then on the root
npm run dev
this will run the both backend and frontend