Welcome to the Magix user to user forums, so not a contact for any Magix staff and your video convertor product is not ours!
I assume you have an old copy of Video Easy, or Rescue Your Videotapes, or similar? Does this transfer the VHS footage direct to DVD or do you have an option to "edit" that video on your computer? If you do have that latter option, what format are the files in when saved to your computer? They will most likely be, I think, either DV-AVI or MPEG-2.
Both of the current main video products from Magix, Magix Movie Studio and Video Pro X, will allow you to convert footage from VHS tapes to your computer if you have access to the appropriate hardware; it is possible that the existing cables that connect to video and to the PC will work for this but you would be best advised to look for a higher quality convertor (i.e. that "hardware" that goes between the VHS player and your PC). The resulting files will most likely be in DV-AVI format, which either MMS or VPX will very easily and quickly convert to whatever type of .mp4 you wish to produce. (.mp4 is a "container" format. The actual video files produced by the conversion process can be of whichever type(s) the user chooses.)
However, can your current software convert your files to .mp4? In other words, the files you have previously transferred from the VHS tapes to your computer, can you use your existing software to convert them to .mp4? I suspect possibly not, especially if that software is quite old!
Do please tell us exactly which software you currently have, however old it may be!