Need help with mongoimport with MongoDB Atlas

I have a MongoDB Atlas (free) account. I am able to connect to it using mongo shell as well as node.js applications. However, I am unable to connect to it using the mongoimport utility. The problem is with the --uri parameter value. There may be a mistake in my understanding of the format of this parameter, or I am making some really silly mistake. This may take someone experienced with this just a few minutes of time, but please budget for 60 minutes in a call. In the call, after fixing the immediate problem, I would like you to help me with various options in mongoimport and mongoexport.