I use Google Music Manager to transfer music files from my iTunes Music folder to my Google Play Music library, so I can play them on my Android device. GMM is a program that was seems to have been designed for Windows 7 and hasn't been updated since, but I can't find anything else that transfers files from the iTunes Music folder to Google in some semblance of order. When I set GMM to transfer only selected Playlists from the iTunes Music folder, what comes across is a mish-mash that only faintly resembles the Playlists I requested. (There is no way to select artists, genres, podcasts or songs for transfers. It's either Playlists or the whole shebang.) What I get after it takes a couple of hours to transfer 1500 files are the requested Playlists - Yaa! - plus many hundreds of duplicates, many songs that aren't in the requested Playlists, and hundreds of unrequested Podcasts. IOW, a disorganized mess.
It took me hours to manually delete all the duplicates in Google Play Music. iTunes can spot a duplicate in a millesecond; GPM doesn't know such a thing exists.
There is no way to transfer podcasts from the iTunes podcasts folder to a podcast folder in GPM. They just appear unsummoned in the GPM Songs department. Trying to shuffle Songs in Google Play is hopeless because the Songs listing contains both songs and podcasts. To shuffle songs, I had to make a Playlist that contains only songs and no podcasts. As yet, I have been unable to place all my podcasts in one place. They're scattered randomly in the Songs listing.
You'd think an advanced and successful company like Google would be able to produce an efficient song-management app that could transfer a pre-organized library from a Windows folder to Google Play Music. Music Manager ain't that program.