Syncing Local Files to Spotify on an iOS device

[GarackTheMad]

I'm having trouble syncing local files from my desktop PC to Spotify on my iOS device. I have these same local files in my iTunes library on that device if it helps. Otherwise, I've browsed other solutions on here, and I cannot seem to get it to work. I've already disabled the Windows Firewall for Spotify. I've also set the playlist filled with the local content to download on the iOS device. When I open the playlist on the iOS device it appears as empty.