This is a user forum, not Magix Support, so no one here sent you a serial number.
What is wrong with the one that Magix sent you? You say it doesn't work, but was there no error message? Did you use the serial number with the correct program? Is it really Movie Edit Now?
How about providing an easy way to find how to contact you for help via email
Did you try clicking on Support at the top of the forum? It takes me 6.5 seconds to get to the email page as you can see in the video. It's not going to get easier than that.
Your question about the name of the program (which I would agree with!) prompted me to do a little research. It turns out Movie Edit Now is a Magix product offered, free, through the Microsoft Store! I'm not personally interested in downloading and installing it but it seems to be an extremely basic video editor!