Hello,
phpdocx uses $_SERVER['SERVER_NAME'] (https://www.php.net/manual/en/reserved.variables.server.php) for license checking. Maybe your server is not returning that information (https://stackoverflow.com/questions/465504/server-addr-undefined-index). Please set it to your server configuration or manually. The same GenerateDocx class is used for CreateDocx and CreateDocxFromTemplate (this class extends CreateDocx).
If you can't add that information, please edit GenerateDocx.php and comment that line.
Regards.