category__in not working on custom post type

category__in will never work as you aren’t making use of the build in taxonomy category. You are actually making use of a custom taxonomy called tagbbt. Take a look at this post, I have explained what the differences are

For custom taxonomies, you need to make use of a tax_query

Here is an example

$args = array(
    'post_type' => 'bbt',
    'tax_query' => array(
        array(
            'taxonomy' => 'tagbbt',
            'field'    => 'term_id',
            'terms'    => array(90,89),
        ),
    ),
);
$query = new WP_Query( $args );