You can only assign widget areas to the primary and secondary sidebars, using that plugin. The markup surrounding the widget area never changes. The only thing that changes is the dynamic content that displays within the pre-existing sidebar locations.
It really is easy to add a new widget area to Genesis child themes, but you will need to do it programmatically ~ here’s a really good explanation how to do that by ‘Nick The Greek’ ~ How to Add a Widgeted Area (a.k.a. Sidebar)