Tell SearchWP to extract PDF contents of a file uploaded to an ACF file upload field and store that content with the post itself as custom metadata, not the Media entry

gistfile1.php

<?php

/**
 * Extract PDF content from a file uploaded via ACF File field (where
 * the actual data stored is only the Media ID) and store PDF
 * content as SearchWP 'extra' metadata so it can be included in
 * searches and attributed to the post itself, not the Media entry
 */
class My_SearchWP_Customizations {

	// ACF field name for PDF upload field
	private $my_acf_field_name = 'acf_pdf_field_name';

	// custom field key used by SearchWP to store PDF content with the post
	private $my_searchwp_acf_pdf_custom_field_key = 'searchwp_pdf_content';

	/**
	 * Initializer; hook into SearchWP where necessary
	 */
	function init() {
		// hook into SearchWP's indexer
		add_filter( 'searchwp_extra_metadata', array( $this, 'maybe_extract_pdf_contents_from_acf_field' ), 10, 2 );
		add_filter( 'searchwp_custom_field_keys', array( $this, 'add_custom_pdf_content_metakey' ), 10, 1 );
	}

	/**
	 * Callback from the SearchWP indexer to extract content from a PDF uploaded to the specified
	 * ACF upload field
	 *
	 * @param  array $post_metadata  The post metadata to index
	 * @param  object $post_to_index The post object currently being indexed
	 *
	 * @return array                 The post metadata to index
	 */
	function maybe_extract_pdf_contents_from_acf_field( $post_metadata, $post_to_index ) {

		// at the very least we need either the SearchWP indexer, or SearchWP Xpdf Integration
		if ( ! class_exists( 'SearchWPIndexer' ) && ! class_exists( 'SearchWPXpdf' ) ) {
			return $post_metadata;
		}

		// check for ACF field value to work with
		$pdf_object_id = get_field( $this->my_acf_field_name );

		// if there's no ACF value, there's no sense in continuing
		if ( empty( $pdf_object_id ) ) {
			return $post_metadata;
		}

		// grab the Media post object that is the PDF
		$pdf_object = get_post( absint( $pdf_object_id ) );

		// make sure it's a PDF
		if ( 'application/pdf' == $pdf_object->post_mime_type ) {
			return $post_metadata;
		}

		// if Xpdf Integration is enabled, we can use Xpdf here
		if ( class_exists( 'SearchWPXpdf' ) ) {
			// use Xpdf to parse the PDF
			$xpdf = new SearchWPXpdf();
			$xpdf->init();
			$pdf_content = $xpdf->extract_pdf_content( '', get_attached_file( $pdf_object->ID ) );
		} else {
			// fall back to built-in PDF parsing and grab the PDF content
			$indexer = new SearchWPIndexer();
			$indexer->set_post( $pdf_object );
			$pdf_content = $indexer->extract_pdf_text( $pdf_object->ID );
		}

		// add it to the pseudo-metadata array
		$post_metadata[ $this->my_searchwp_acf_pdf_custom_field_key ] = $pdf_content;

		return $post_metadata;
	}

	/**
	 * Make sure our 'extra' metadata key is visible in the Custom Fields dropdown on the settings page
	 *
	 * @param  array $keys The Custom Field keys to show on the settings screen
	 *
	 * @return array       The Custom Field keys to show on the settings screen
	 */
	function add_custom_pdf_content_metakey( $keys ) {
		$keys[] = $this->my_searchwp_acf_pdf_custom_field_key;

		return $keys;
	}
}

// liftoff
$my_searchwp_customizations = new My_SearchWP_Customizations();
$my_searchwp_customizations->init();

Unfortunately not working for me. Added it in functions.php and replaced the File field name with the field name that I am using for my File field. Also changed the output of the ACF file field to the ID instead of the default option that is Object. Am I doing anything wrong?