How to use SoftwareApllication properly?

Hi there, i was trying to implement the SoftwareApllication model for my posts, but, wehn i try to implement the code in the functions.php, nothing happens.

I’m trying to follow the instructions here: https://blazzdev.com/documentation/rate-my-post-documentation/#filters, but maybe i lack the coding knowledge to do that…

function blazzdev_sa_structured_data( $structuredData ) {
  $voteCount = rmp_get_vote_count();
  $rating = rmp_get_avg_rating();
  $img = get_the_post_thumbnail_url();
  $name = get_the_title();
  $operatingSystem = get_post_meta( get_the_id(), 'myschema_operatingSystem', true );
  $applicationCategory = get_post_meta( get_the_id(), 'myschema_applicationCategory', true );

  $structuredData = '
  <script type="application/ld+json">
    {
    "@context": "http://schema.org",
    "@type": "SoftwareApplication",
    "aggregateRating": {
      "@type": "AggregateRating",
      "bestRating": "5",
      "ratingCount": "' . $voteCount . '",
      "ratingValue": "' . $rating . '"
    },
    "image": "' . $img . '",
    "name": "' . $name . '",
    "description": "' . $name . '",
    "applicationCategory": "' . $applicationCategory . '",
    "operatingSystem": "' . $operatingSystem . '"
    }
  </script>
  ';

  return $structuredData;
}

add_filter( 'rmp_structured_data', 'blazzdev_sa_structured_data' );

Nothing new is shown in the plugin pannel and nothing in post editor.

I’m using a theme called Newspapper and i really need to implement this.

Here is how my functions file looks like: https://drive.google.com/file/d/11zhLunpGP82384YVBH2cE2E4J6zA4Cu_/view?usp=sharing

Any help is welcomed, Thank’s