There is no separate page template as such for the About Us page. You can use either the page template “Full Width” with [segment] shortcode to wrap content and specify full width parallax backgrounds or to keep it simple, just use the “One Column No Sidebars” template to not worry about full width and enter the content through the WordPress WYSIWYG editor.
Also, I would urge you import the sample data and modify the template provided to save time (About Us page is included). Will speed up your site development significantly if you start with sample data or at least have sample data imported in another WordPress installation for reference. You can just create a temporary folder in your server, have wordpress installed on it, import the content and refer to the same for your main site. Hope this helps.