Sorry to hear you've had problems activating your program. There can be various possible causes for this:
Is your firewall preventing the program contacting the Magix server? You will need to check its settings and ensure that contacts to Magix are allowed.
It is possible that the Magix server itself may be off-line. The only solution in this case is to "keep trying" I'm afraid.
I notice you say you uninstalled the original installation before downloading and reinstalling. This should not have been necessary and might have added to your difficulties! Unfortunately, the built-in uninstaller follows the "route" of the log created when the program was first installed; however, some files and folders are automatically created on first run of the program, after installation is complete! Thus the uninstaller does not know they exist so does not remove them! This tutorial, https://www.magix.info/uk/tutorials/fixing-program-issues-after-windows-10-upgrade--1142475/ though written to help users who experienced considerable problems following the Win 10 upgrade, also contains very valuable information in assisting in completely removing a Magix program prior to reinstalling it, especially sections 1 and 2 of the instructions.