I can't load any songs on DJay, it won't detect them

So, I recently installed Djay 2 on my new Android phone and when I opened it up to try it I realized: I don’t have any music in my phone! So I figured the easiest way to get some tunes might be via Google Play. I paid for and downloaded a couple of songs to get started. When I opened my Djay and tried to load the songs, I couldn’t. It won’t find them. The only files available for loading are my whatsapp voice messages. I’ve gone back and forth between Play Music and Djay, checking settings and all but I can’t find a way for the app to find the songs.

Honestly though, you’d think that this would be the easy part. Whatever is happening, it’s pretty stupid that this isn’t more simple, like: download a song, open Djay, load the song. Period. Could I get any help with this? Thanks!