I made sure to register online and type in the serial number correctly and I keep getting the error 14 notice. It's frustrating because I can't even message or call technical support. After all, they made it impossible to find that information.
The error code 14 message means that you're putting a valid MAGIX serial number into the wrong MAGIX product or version/edition eg you cannot use a serial number that is meant for Music Studio into Music Maker, these are 2 different products.
Check that you have the correct product version installed as you have purchased.