Hi Petra , I see the issue. Your WordPress environment has been configured for www.palturai.com, but you have logged in via palturai.com without the www.
Due to browsers policy it cannot load content from different subdomains without the permission 'Access-Control-Allow-Origin' header set.
I personally would recommend you to force the www variant on your website and make sure you are logged in via the www subdomain when you edit Buttonizer. That should be the solution 🙂