create .env folder
add
ATLAS_URI=mongodb+srv://<username>:<password>@cluster0.8sf1t.mongodb.net/<database-name>?retryWrites=true&w=majority
open terminal in anime-list-app folder
cd ./client
npm install
cd ../server
npm install
npm start
After that open second terminal in anime-list-app/client
in second terminal comments
npm start
The web app url : 'anime-list-app.vercel.app'