There have been some problems with installing MongoDB locally, because things change quite frequently.
The truth is, you don't need to install MongoDB in order to go through this course and to build most apps.
You can just use a hosted MongoDB instance using a service called Atlas, as I will teach you in Lecture 80.
This means you can skip Lectures 72-78 (79 is relevant for installing the Compass app).
Happy learning! ✌️