Hi,
You can create the field taxonomy to add the taxonomy for the post on the frontend. Other custom fields will work like that.
For example: the code to creates a meta box and custom fields
add_filter( 'rwmb_meta_boxes', 'your_prefix_function_name' );
function your_prefix_function_name( $meta_boxes ) {
$prefix = '';
$meta_boxes[] = [
'title' => __( 'Post Meta', 'your-text-domain' ),
'id' => 'post-meta',
'post_types' => ['page'],
'fields' => [
[
'name' => __( 'City', 'your-text-domain' ),
'id' => $prefix . 'city',
'type' => 'text',
],
[
'name' => __( 'Taxonomy', 'your-text-domain' ),
'id' => $prefix . 'taxonomy_j6xupbwl47k',
'type' => 'taxonomy',
'taxonomy' => ['category'],
'field_type' => 'select_advanced',
],
],
];
return $meta_boxes;
}
Frontend shortcode: [mb_frontend_form id="post-meta" post_fields="title,content" post_type="page"]
Please read more on the documentation https://docs.metabox.io/extensions/mb-frontend-submission/