How to setup a local development environment?

Hey I want to develop a page inside confluence.
I tried to setup Atlassian User Interface on local machine.
There is a page How to consume aui.
I managed to install flatpack v8.5.1 but some things are not working like Progress Indicators.
What is a best way and most straightforward way to consume aui in latest version?

I found the solution in Codepens.

<!-- External dependencies -->
<link rel="stylesheet" type="text/css" href=""/>
<script src=""></script>
<script src=""></script>
<script src=""></script>
<!-- / External dependencies -->