Confirmed on Motorola Moto E
Bug not occuring on Motorola Moto E Android 5.1 so not sure if this helps. My music downloaded fine no problems.
Also experiencing this on a Motorola Moto E, Android 5.1
Actually that sounds like normal. It's been like that since I can remember at least.
I'm one of the people who were working on this add-on, and first discovered the behavior along with another person also working on it.