Why does my downloaded MP3 files need to be unziped? I don't know why, but for some reason, the google music don't play them directly, everytime, it opens winRAR on my Nexus 5X then plays it.

This only happens to the mp3 that I downloaded from internet, ie. sites like: youtube to mp3, clipconverter.cc

I am trying to make a playlist of youtube podcasts, and for somereason, I need to click the file, it opens winrar, then plays it, and if I uninstall winrar, then i can't play the music...

How do I solve this?  I quite like the current music player native to my nexus 5x, and it's not working out after a few weeks of trying....
Right, when we download the mp3 files using websites like youtube to mp3 etc etc they provide us mp3 songs in zip files. so in order to avoid it, you need to follow few below steps. 

first click on SETTING

then go for DOWNLOAD SETTINGS

then at the end there is an option names MORE OPTIONS

Just check the DOWNLOAD DIRECTLY

that's it, it will solve your issue