What keyword will help me search for music player app that plays by folders? I used to own a galaxy s3, and the default music player had that feature. Then I upgrade to a nexus 5, and it seems like it's missing it.

I'm huge fan of organizing my music by folders on my phone's hard drive, so I need an app that can do that, or figure out how google music app does it.

How can I search for these kinds of apps?
A good keyword combination is already given by your question: a music player which should play folder-wise should be found using the keywords "folder play", "folder player", and similar combinations. In fact, there are even some players named exactly such, e.g. Music Folder Player, Folder Player, and many more.