Thanks for purchasing Circle Flip and sorry for any inconvenience.
Please check the php_memory limit. That have been the issue with some having the same trouble.
Kindly contact your hosting providers and ask to update php_memory_limit to 256 (even temporarily for you to install the demo)
Please let me know if that doesn’t work, and include admin access to the installation if possible.
Another quick alternative will be loading the hosting page template directly from the page builder as in the screenshot below: