To initialize the Javascript, see the instructions in the Setup section at the top of the navigation. If you want it to be collapsible, make sure to initialise it (it's separate from the basic sidenav Javascript)
Our side navigations is meant to be fixed on the left hand side of the screen, not scrollable. This layout can be achieved using flex (recommended) or floats, giving the main content of the page `overflow-y: auto`. By default the `height` is `100vh`, you'll have to override this in your CSS if you have different requirements. Our navigation is responsive, so it will automatically (and without JavaScript) create a panel off-screen on small devices. The trigger to open this panel can be put virtually anywhere, giving it `id="Vlt-sidenav-mobile-trigger"` automatically makes it look for the sidenav with `id="Vlt-sidenav"`. You may have to play with the width of the frame to see the behaviour.