Unclear instructions in software documentation

Hi everyone, a couple days ago I joined a new team and got issues setting up my machine for development on that new project. I followed instructions and skipped one that was marked as optional. Except it wasn’t really optional but the doc was designed for two audiences so stuff was mixed up. Eventually I wrote a new doc for dev onboarding and a separate one for users of the API from my new team. What would you do in that situation?

Also I wrote a post about the experience; https://www.codingnagger.com/2020/01/09/optional-steps-documentation/