The usual reasons for the non-receipt of emails of this kind are:
The email address you used to register with was not typed in completely correctly. Have you received ANY email confirmation from Magix, which would suggest your email address was correctly recorded by the Magix server? If not, it is possible there was an error. If so, I think you will need to contact customer services via http://support@magix.com, explain the situation and ask them to correct the records in order to ensure you receive the needed activation code.
It is possible that your ISP (Internet Service Provider) or its email server may be marking any emails from Magix as Spam, and so refusing to allow you to download them. In this case, you may need to discuss the problem with your ISP so that these emails are not blocked. Also, have you checked your own email's "junk" folder, in case your own email client has decided the message from Magix is spam?
Please post back and let us know whether you have been able to resolve this problem.
I did not have an activation code in the email, only a coupon code. How do I get the activation code? I just received the link in another email. Thanks anyway...
Please read my earlier reply in this thread (which is actually more than three years old) and follow the advice given. Alternatively, use the Support link in the header of every forum page to contact Magix Sales/Customer Service.