I would stick with studying for step 2. You'll have more than enough time to listen to EM rap third and fourth year. If you want something EM that will help you think of differentials and etc I would try EM basic but that's going to be over kill for a second year. Prioritize my friend!
You are fine listening to it as a medical student; however, you are not going to get much out of it. EM:RAP tends to focus more on cutting edge topics, day-to-day EM issues like throughput and pro-tips for basic procedures you won't be doing until you're a resident, and they frequently do segments on medical malpractice cases. You need to have a firm understanding of the basics of EM care and experience in the ER to get the most out of it.
EM:RAP has recently developed something called C3 (core curriculum) which is probably a decent listen for medical students, as a MS2 it still probably isn't super beneficial quite yet, but I would start with those.