The registration part of the website says it is already registered, but when I try to create an activation code that part of the website says it isn't registered.
@Phillip-Milne You should see a serial number in your Magix user account. Enter your e-mail address and the serial number during the first program start and the program should contact Magix' servers and should be unlocked.
There is no need to create an activation code.
But it might not run well or at all on Windows 10 because the program is very old.