Hi @TheoSchipper,

I hope you are well today and thank you for your question.

There isn’t any direct demo download.

Please make sure you are using latest version of PHP on your server by referring the information provided in the following pages.

https://www.wikihow.com/Check-PHP-Version
http://php.net/supported-versions.php

You can resolve the 500 internal server error as described in the following page.

http://freewptp.com/fix-wordpress-issue-internal-server-error/

Best regards,
Shufflehound team