If you didn't receive an email following setting up your Magix account (if not already in existence) and registering your Trial version of Movie Edit Pro (not "movie maker") the most common reason is because you made a mistake in entering your email address to create the account.
So, you need to access your account via the main Magix web site and check the details stored there. You may need to "amend" some of those details. (If you have successfully registered you should also find a list of registered products, which includes details of your serial number.)
If you cannot access your account you need to email shop@magix.net and explain the full details of your problem.