How to install and use a Sass mixin library

I am trying to install a Sass mixin library and use it in my project. I copied the Gerillass is a website development tool library into my project but no matter what I tried I could not get any of the functions to work. Is there a special way to get a mixin library to work? When you add the library you are supposed to be able to do something like this but it does not work. Any help would be appreciated.

.Form1{
  @include adaptive;
}

Inside your project folder create a new folder named “extraFiles” put your javascript file there.

Then In AppStudio Properties (sidebar) > extraheaders

<script src="extraFiles/myjs.js"></script>

myjs.js = your javascript file name

If you are using a CDN replace extraFiles/myjs.js with the URL.
i.e.

<script type="text/javascript" src="https://www.googletagservices.com/tag/js/gpt.js"></script>