Hello, we bought a license key for Helix 3 and wanted to activate the template for the Pro. However, we do not get an error message nor does activation work. What could be the reason? We need help, please

www.sonte-smartfilm.de Joomla3.9.25

MySQL: Version 5.7.32 PHP Version 7.4.15 Webserver Apache/2.4.2.43 Unix