Problems with syncing to my phone

[vakarian1999]

So it seems that to download "local file" songs off of your computer to your phone there was a devices tab and you just had to plug your phone to your computer. I put the local file in a playlist on my computer and on my phone it is greyed out. My problem is after pressing "Available Offline" it doesn't download the song it just says Waiting to download. I've tried plugging in my phone, putting the song in a playlist alone, and downloading it just through cellular data and wifi. I don't know what else to do.