Create a MongoDB instance on Atlas

Create an account on Atlas (opens in a new tab). Follow this tutorial (opens in a new tab) to setup a MongoDB instance.

The free tier can be enough to start.

Once created, get the connection string from "Database Deployments" -> "Connect"

Then click on "Connect to your application" -> Drivers -> "3. Add your connection string into your application code".

Once you copy the connection string, fill the MONGODB_URI variable in the .env file