Simply put, Edge One-Pager is only a simple page which categorizes a page into different sections.
Use this link: WPBakery Page Builder to know how to use WPBakery Page Builder and refer to this link: https://webnus.net/deep-premium-wordpress-theme-documentation/king-composer/ for King Composer.
First, you should create a page, check this link: https://webnus.net/deep-premium-wordpress-theme-documentation/create-new-page/ then, by adding a section, you can complete the page that you are creating step by step. After creating each section (our suggestion is full height section for a better appearance) go to page option settings and enable the options Edge Onepager. For more information on page option you can check this link: