1. Go to this page and download the library: Download airesvsg/acf-to-rest-api library. Choose the download type require.
2. Extract the ZIP file and open the index.php.
3. Add this code to the index.php.
<?php
require_once('vendor/autoload.php');
/* Start to develop here. Best regards https://php-download.com/ */
// Enable the option show in rest
add_filter( 'acf/rest_api/field_settings/show_in_rest', '__return_true' );
// Enable the option edit in rest
add_filter( 'acf/rest_api/field_settings/edit_in_rest', '__return_true' );