1. Make sure the Cron functionality is enabled on your server and is not disabled on your site.
2. We will do our best to fix it asap. Meanwhile, you may downgrade PHP version to 7.2 on your server to use the plugin successfully. We will notify you when Demo Builder plugin is compatible with PHP 7.3 Thanks.
Please, note that we do not provide support in the ticket system on weekends, we are also sorry for any delay. Nevertheless, our support agent John Davis answered you in the ticket system. Please, check spam folders.