How to get downloaded music onto iPhone from iTunes library?

So I've downloaded ace hood s mixtape from datpiff.com and I extract the files and dragged it to the iTunes library. But the problem is that when I click on the MP3 file and try to add it to my phone it shows the song but with a empty circle next to it and it won't download. So if anybody could help me with this I would appreciate it.

You normally transfer songs by syncing them. Have a look at these help articles from iTunes support
https://www.apple.com/...s/syncing/