The way our Auto-Layout plugin works is by hooking into the internals of Sketch and enforcing layout rules in real-time (i.e when the mouse moves). If someone doesn't have the plugin installed, the Sketch file can still be opened but they won't have the code that enforces the layout rules, so yes it will look and behave differently.

So while using Auto-Layout can save an enormous amount of time creating UI, it definitely needs to be used by all designers that work on the file.

In terms of exporting to other parties such as Zeplin, we have a feature that turns off all the layout rules just before exporting. If you have tried it out here it is: https://animaapp.github.io/docs/v1/launchpad/faq.html#Export...

And thank you for the kind words!