Did you follow the guidelines when entering your password? You will find this in the registration form when you register.
Java Script / Cookies
Have you activated a Java Script Blocker or switched off the acceptance of cookies in your browser? Both functions must be activated for a successful registration.
Activate Java Script
So that the system can remember that it is you who has logged in, so-called session cookies must be allowed. Without this, the registration will not work. Allow this acceptance of cookies within your browser settings, clear your browser cache and try again.