custom post type section selector

Ok, as requested.

Create an ACF field.
Add a repeater field.
Inside the repeater, add a text field with name title.
Inside the repeater, add an URL field with name link.

$menu_items = get_field( 'repeater_field' )

if ( $menu_items ) {
    echo '<ul>';
    foreach( $menu_items as $item ) {
        echo '<li><a href="https://wordpress.stackexchange.com/questions/298949/{{ item.link }}">{{ item.title }}</a></li>';
    }
    echo '</ul>';
}

You can then link to any sub-pages you have created.