I cant seem to get it working. I keep getting "You must be signed in to make or propose changes" and other errors. I have the .vim in plugin folder.

I'm so confused, why does this need a specific thing?

I'll just fullscreen {g,mac}vim and only have one pane if I'm set on doing this.

The idea is to remove all the distractions (tabs, status bar, split screens etc.) and just focus on one thing. It also centers the content (which is non-trivial to do in vanilla vim) and includes special colors and settings to make Vim look like iA Writer when you are editing Markdown or reStructuredText.

Of course, it's not for everyone, but I like it when I am writing text or just editing one code file.

If you've fullscreened the vim container (eg, gvim macvim) then

    set lines=80

Will center it. Not super complex in vanilla vim :)