Local File not Working on Galaxy S7 Edge

[ererwild8]

Hello. On my Windows desktop, I added some local files into a playlist. I was looking forward to hearing them on the go when I don't have access to Wi-Fi. As I went into the app after transfering over the 4 local files into a playlist, they wouldn't play on my Galaxy S7 Edge. 

Why are the audio clips not playing? Is there anything possible that can be done for me to be able to listen to the 4 songs?

Christian