custom fields

Hi, i have just order custom field plugin, but it looks too complicated…
I M FOLLOWING THIS INSTRUCTIONS https://wpadverts.com/documentation/custom-fields/

So far i registered custom field with this code and while editing it looks it s working.

add_filter( "adverts_form_load", "my_adverts_form_load" );

function my_adverts_form_load( $form ) {

    if( $form["name"] != "advert" ) {
        return $form;
    }
    
$form["field"][] = array(            
        "name" => "Brand",
        "type" => "adverts_field_checkbox",
        "order" => 25,
        "label" => "Brand",
        "is_required" => false,
        "validator" => array( ),
        "max_choices" => 2,
        "options" => array(
            array("value"=>"1", "text"=>"Mercedes"),
            array("value"=>"2", "text"=>"Audi"),
        )
    );}

NOW, i ve add this code to functions.php

add_filter(“manage_edit-advert_columns”, “my_adverts_edit_columns”, 20);

function my_adverts_edit_columns( $columns ) {
$columns[“brand”] = “Brand”;
return $columns;
}

add_action(“manage_advert_posts_custom_column”, “my_adverts_manage_post_columns”, 10, 2);

function my_adverts_manage_post_columns( $column, $post_id ) {
if($column == “brand”) {
$cf = get_post_meta( $post_id, ‘brand’, true );
if(empty($cf)) {
echo “Empty“;
} else {
echo ““.$cf.”“;
}
}
}

I CAN SEE THE COLUMN BUT IT SAYS EMPTY instead of showing the value.

What do i do wrong?
Displaying on Ad Details Page is not working either.

thanks for help