Songs that I have downloaded after the initial install of BB Link don't show up.

I want to be able to use my phone as an MP3 player, but am finding barrier after barrier in trying to do so. I am using Mac OS X Yosemite and BB10. Nothing I have downloaded on iTunes or otherwise after I installed BB link are showing up. In fact, pictures I have imported since then are also inaccessible.

I know this doesn't solve your issue with Link, but I never use Link to manage my music or pictures. I always drag and drop them myself. Can't you find the iTunes folder and drag your music to your SD card? I do that on my PC and I'm sure i did it when I had my Mac as well.