best cloud storage for mp3 files

Hi all!
I have a question about cloud storage. And I have some spicific requirements.

My brother makes music and sends me songs via email in mp3 format. I have stored a file in Onedrive and I like it. I do this mainly because I post the songs to Facebook for my friends/family to hear. I leave them in mp3 format rather than convert them to video.
I'm not running out of space but I'd like to avoid that worry/possibility.

My questions are:

1. What is the best most acceisible cloud storage service?
2. How much stohage do you get for free? To put it in perspective, the last file my brother sent me was 6Mb.
3. Which ones work with the Files app?

I would put them in Icloud, but some of my friends/family use Ios. and some use Android.

Any help would be appreciated! Thanks in advance!