Add categorys to custom post type not working

That is not the way to register a Taxonomy.Please find the code below to register a Taxonomy for a custom post type :-

$args = array(
    "label"                         => "Butik Categories",
    "singular_label"                => "Butik Category",
    'public'                        => true,
    'hierarchical'                  => true,
    'show_ui'                       => true,
    'show_in_nav_menus'             => false,
    'args'                          => array( 'orderby' => 'term_order' ),
    'rewrite'                       => false,
    'query_var'                     => true
);

register_taxonomy( 'butik-category', 'butik', $args );

Hope that solves the problem.You can also use plugins like Custom Post Type UI to easily create Custom Post Type.Here is the link :- https://wordpress.org/plugins/custom-post-type-ui/
Hope that helps 🙂