Trying to get digital music from Amazon to play on my phone

I've done this many times before but for some reason, it now doesn't seem to be working. I'll purchase a song from Amazon, a digital MP3. This is not off the Amazon Music app or Amazon unlimited or whatever they're calling it. I go to my MP3 library and the purchased music and I download it. The MP3 plays fine in windows media player. However, once I transfer it over to my phone, my music player does not seem to be able to find the MP3's I've just downloaded. I've restarted my phone, deleted and re downloaded and attempted transfer the files again. No change.

I haven't downloaded any songs from Amazon for several months and this is the first time I've run into this issue with getting MP3 files from my computer to my phone. I've researched it a bit and it seems like there something with DRM's? Is this something new they implemented?

If this is true, and I won't be able to play any music from Amazon other than on the Amazon music app, can any of y'all recommend a better website to purchase MP3's from that won't give me this issue?