How to assign Woocommerce order by custom fields？ - woocommerce

Question

My Woocommerce store with 5 store managers, I use the Local Pickup plugin, it automatically generates custom fields.
How do I correctly assign orders to them and make them invisible to each other's orders？
I have found a similar function, but can't work for custom fields.
function before_checkout_create_order($order, $data) {
$idp = get_post_meta( $order_id, 'pickup_name', true );
$store_manager_id = '';
$belgium_region = ['3'];
$czech_region = ['2'];
$uk_region = ['1'];
if (in_array($idp, $belgium_region)) {
// Manually assigning the _store_manager_id using the user id, yours will differ
$store_manager_id = 7;
} else if (in_array($idp, $czech_region)) {
$store_manager_id = 3;
} else if (in_array($idp, $uk_region)) {
$store_manager_id = 2;
} else {
$store_manager_id = 1;
}
$order->update_meta_data('_store_manager_id', $store_manager_id);
}
add_action('woocommerce_checkout_create_order', 'before_checkout_create_order', 20, 2);
function custom_admin_shop_manager_orders($query) {
global $pagenow;
$qv = &$query->query_vars;
$currentUserRoles = wp_get_current_user()->roles;
$user_id = get_current_user_id();
if (in_array('shop_manager', $currentUserRoles)) {
if ( $pagenow == 'edit.php' &&
isset($qv['post_type']) && $qv['post_type'] == 'shop_order' ) {
// I use the meta key from step 1 as a second parameter here
$query->set('meta_key', '_store_manager_id');
// The value we want to find is the $user_id defined above
$query->set('meta_value', $user_id);
}
}
return $query;
}
add_filter('pre_get_posts', 'custom_admin_shop_manager_orders');