When I first started writing this post the latest version of acorn was 5.3.0, however as of the latest edit of this post there is now an 8.x of this project. So if the code examples I have here break that might be a good reason why. Always check what version is being used, and not just with Acorn, often code breaking changes can be introduced into a project, and this should almost be expected when it is a new major version.
Just like any other node.js project I just created a new folder, did an npm init, and installed the latest version of acorn.
I then also made a demos folder, and made my first demo called basic.js. It is a usual practice of mine to start out with a demo like that when trying out a project of any kind.
When calling this script from the command line I end up getting this: