What exactly is not working? The Juicebox skin should produce a full browser page (which always fills the browser's viewport no matter what its shape or size) and your album seems to be doing this OK (viewed in a desktop browser and on an iPhone).
The responsive setting in the 'Tree' section refers to a specific option for jsTree themes (jsTree is the navigation tree used in the skin) and doesn't refer to the entirety of the web page.
It is documented here: https://www.jstree.com/api/#/?q=$.jstre … responsive
$.jstree.defaults.core.themes.responsive
a boolean specifying if a reponsive version of the theme should kick in on smaller screens (if the theme supports it). Defaults to false.
If you need to have the tree text scaled up for mobile devices, then you could try adding a <meta> viewport tag (as below) to the <head> section of your album's 'index.html' page (but please note that this is untested).
<meta name="viewport" content="width=device-width, initial-scale=1" />