从私人网站获取postdata

So, I'm using wordpress and I have a site set to private on which I have multiple advance custom fields. But when I want to call them I don't see anything unless I set the page to either public or I'm logged in as administrator.

This is my code to set up postdata

    $the_query = new WP_Query( 'page_id=1234' );
            while($the_query -> have_posts()) : $the_query -> the_post();
                    setup_postdata( $the_query );
                    do something;
            endwhile;