Citadela Listing plugin uses standard WordPress users, user roles, custom post types and categories. By default, users have to register to be able to administer their items. The Easy Admin features can simplify standard WordPress administration to make it easier for beginner users.
The beauty about Citadela is that theme and plugins are universal. We only used standard WordPress features for everything and strictly followed WordPress codex.
You can therefore use 3rd party plugins and solutions together with Citadela. The following two popular plugins will allow you to insert information into WordPress custom post types from the frontend: