Add wp flexible map before below the header in a Customizr page

flex_map_after_header.php

add_action('__after_header', 'my_map', 20);
function my_map(){
  /* use page slug or name or id */  
  if ( ! is_page('sample-page') )
    return;
  /* Shortcode example from https://wordpress.org/plugins/wp-flexible-map/installation/ */
  $map = '[flexiblemap center="-34.916721,138.828878" width="100%" height="400px" zoom="9" title="Adelaide Hills" description="The Adelaide Hills are repleat with wineries."]';

  echo do_shortcode($map);
}