I have installed Magix Movie Edit Pro 15 on a new computer that we purchased and I can not get codes for MPEG2-codec and MPEG4 - codecs. This is really frustrating cause I can't do something that I need to do because none of the answers I found online seem to help.
Presumably you had MEP15 installed on your own computer?
Which version of MEP15 do you have - disc or download?
Licensed codec activation will be requested when you add a video clip to the timeline and the codec is not available. If you have the download version of MEP then the codec have to be purchased (IIRC). The disc version will only ask for them to be activated.
See Tasks, Activate additional functions, Codec Activation in the menu bar?