I see the trouble. The app will need access to the XML-RPC file for your site, but it’s currently not loading, which means the app isn’t able to connect. I recommend you check the following:
– Can you see the /xmlrpc.php file at the root of your WordPress installation when accessing your site via FTP? If you don’t, then please try re-installing WordPress. You can do this by going to the Dashboard -> Upgrades page, then click the “Reinstall” button.
– Do you use any security plugins that may block access to this file? If so, could you try to disable the rule that blocks XML-RPC in them? You might also want to check your site’s .htaccess file for any rules that might be blocking access to the xmlrpc.php file.
– Does your hosting provider block access to this file? If you don’t find any plugin that may block access to the file on your site, I would recommend that you get in touch with your host.