Have you carefully followed ALL the instructions in that linked post? They clearly include details of how to create that Activation Code.
Have you also read the whole thread and seen the responses of other users of Sony software? There are a number of solutions suggested to enable you to receive the code you need.
Some versions of SF-9 (AS or lite) were included with Sony turntables and were different in terms of activation and may not work with the 'new' procedure. I do not have one of those unique versions to test and I do not know if Magix support can help in this case but you can try and it could take a while for Magix to respond. It may be time to upgrade to a more recent version, If you can find a preowned version, make sure it includes the activation serial and the email address it was registered to.