downloading apple music library to mojawa headphones

I'm trying to add music to my mp3 player headphones. I got headphones for my swim workouts. Due to the nature of water, apparently, bluetooth can't transmit through the pool. So, in order to use my headphones while I swim, I have to transfer music onto them and use it as an mp3 player. Back in the day, I had an ipod, so I was thinking I could just drag and drop like it's 2008... Clearly, that didn't work. How do I transfer music onto my headphones so that I can use them as intended?