The project is made of three components

1. Frontend - written in react

to run use

cd client
npm run dev
# or 
npm run preview

2. Headless CMS (Sanity)

to run use

cd ecom
npm run build
npm start

3. Backend - written in express

to run use

cd server
npm run dev
# or
node server.js

also do make sure to fill in appropriate api keys for stripe, mongo database and backend apis in client in respective repos