Follow the detailed instructions inside the 3 Part Getting Started video series. That video implements the latest and greatest.
When I launched Foundation v1.5, I wanted to change how Site Styles worked so that it used the new great things that came with Stacks 3. Then only way to do that without breaking all existing sites was to deprecate the old version and rename it “Site Styles (Legacy)” By deprecating the stack, all existing instance of the stack would continue to work indefinitely. However, it also means that it was not getting any of the new features. In order to get the new features, users would have to add a new instance to the page and re-configure it.
I hope that this helps.