i wanted to download all my itunes library with one click instead of going one-by-one
here’s how: in music app on your mac, create a new “smart playlist”, select rule “purchased” as true and rick the updating checkbox. now i have a playlist with all my itunes purchases. in your iphone, open the music app and select the playlist you just created. click the download button and to you’re good to go!
hope this helps you find and download your complete itunes library to your iphone!