To my knowledge you can use zymic as a store front, you would be best off reading through the TOS, http://www.zymic.com/free-web-hosting/tos/
. Keep in mind though that you are not allowed to sell anything you do not have permission to sell. If you are selling beats you may only sell your own beats and beats that you were given permission to sell. Also zymic does not allow mp3's to be uploaded to their server. Therefore you would have to host you music else where.