// Enqueue JS and pass ajax_url + nonce
add_action('admin_enqueue_scripts', function () {
    wp_enqueue_script('pr-custom-ajax', plugin_dir_url(__FILE__) . 'admin.js', array('jquery'), null, true);
    wp_localize_script('pr-custom-ajax', 'myAjax', array(
        'ajax_url' => admin_url('admin-ajax.php'),
        'nonce' => wp_create_nonce('pr_download_nonce')
    ));
});

// AJAX callback for property download
add_action("wp_ajax_pr_import_auth", "pr_import_auth");

function pr_import_auth() {
    if (!isset($_POST['security']) || !wp_verify_nonce($_POST['security'], 'pr_download_nonce')) {
        wp_send_json_error('Unauthorized request');
    }

    $pr_import = new pr_properties_class();
    $pr_import->download_xml();

    $data = array(
        'action' => 'delete',
        'chunk' => 0,
        'size' => 1000
    );
    update_option('pr_api_info', json_encode($data));

    wp_send_json_success('Properties downloaded');
}{"id":162,"date":"2015-04-16T13:58:30","date_gmt":"2015-04-16T13:58:30","guid":{"rendered":"http:\/\/demo1.wprentals.org\/?page_id=162"},"modified":"2015-04-16T13:58:30","modified_gmt":"2015-04-16T13:58:30","slug":"properties-list-half-map","status":"publish","type":"page","link":"https:\/\/www.odmor.webexperts.me\/en\/properties-list-half-map\/","title":{"rendered":"Properties List – Half Map"},"content":{"rendered":"","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"open","ping_status":"open","template":"property_list_half.php","meta":{"inline_featured_image":false,"footnotes":""},"class_list":["post-162","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.odmor.webexperts.me\/en\/wp-json\/wp\/v2\/pages\/162","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.odmor.webexperts.me\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.odmor.webexperts.me\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.odmor.webexperts.me\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.odmor.webexperts.me\/en\/wp-json\/wp\/v2\/comments?post=162"}],"version-history":[{"count":0,"href":"https:\/\/www.odmor.webexperts.me\/en\/wp-json\/wp\/v2\/pages\/162\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.odmor.webexperts.me\/en\/wp-json\/wp\/v2\/media?parent=162"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}