Sorry to hear you've experienced problems in completing your purchase. Exactly what are you trying to buy? If you are wanting to pay by card, either credit of debit, are you aware of this post?
However, the error message you are seeing is not what I would expect to see if there is a problem with the 2 Factor Authentication system, I think. It may be that there is simply some sort of problem with the payment server. Is the actual wording of the message exactly as you gave it in your post?
If the problem has not resolved itself within the next few hours, you could try emailing infoservice@magix.net and asking for their help. But please bear in mind that Magix is based in Germany and you should not expect any direct reply for at least 16 to 18 hours from the time I am writing this.