Just to confirm there are two options in that lab session and you only need to do one. If you have already imported the data into an Atlas cluster then you are finished as you only need to be one or the other options.
If you are running MongoDB on your machine, can you confirm that you followed the instruction on this docs page for your operating system? This will run a single mongod instance on port 27017 on your local machine.
Can you let us know which of the two types of deployment you are using for the course (Atlas or locally installed MongoDB)? Can you also confirm if it is locally installed that you have followed the instructions for your operating system for your machine?