Hi Juraj,
thank you for reporting this!
You don't need to register somewhere, schedulix is free. The sources are available on GitHub and the rpms are provided as a service.
But lately I've been securing our web site, which is more a duty than a luxury these days, unfortunately.
Obviously I've made a mistake and restricted access a little too enthusiastically.
I'll fix that today.
Sorry for the hassle.
Best regards,
Ronald