Make sure you are in - MERN_A_to_Z_Client/mern_a_to_z_client/ directory & type the following command
$ npm install
$ npm start
To Explore all features in this project you need to connect the server first. Here you will find the necessary files (backend/server).
GitHub Repo - Backend/Server
https://github.com/nurislam03/MERN_A_to_Z
Read My Article about this server side coding