A sitemap page is a staple and an SEO essential for any site with a good amount of varied content. There are a lot of plugins out there that come with pages and pages of individual options customisations, usually missing the one or two things you actually want, and overcomplicating the whole process. It is very simple to build a basic sitemap page using a couple of basic queries and loops that are probably already used throughout the rest of the site.
Sometimes after creating additional custom post types in WordPress, the option to add them to a menu in the admin menu builder will not be there. This is easily solved.