The rapper/singer is not relevant to what you can do with Music Maker with respect to selling beats.
If you are using any of the Soundpool loops, and do not have a Commercial licence for every Soundpool a loop(s) has been used from, then the answer is a definite no.
If you created the beats using the MIDI Instruments, composed and played by yourself, and it is an original composition, then you can do what you like with them.