I would like to start with the fact that I am new to Trellis AND Vagrant. I just use the built in apache on a Mac when using wordpress. Trellis seemed so much easier so I decided to try to learn it.
I am going to go through the pages and mention what I got snagged on, as well as where I finally got stuck.
We link to the official install/download pages for the dependencies in Trellis. It’s bad practice and redundant to replicate the official documentation for each dependency: updating the instructions would take time away from developing the features in Trellis, and the instructions will quickly become outdated when newer versions of the dependencies are released.
On the first page of the docs we link to a fully working example of a Trellis based project: https://github.com/roots/roots-example-project.com
This example project gives every command and the folder to run it from. Did you read through this?