Downloading YouTube Videos as MP3 Files on iPhones

Gday guys,

I've just recently bought a second hand iPhone 5c. I've been an Android user throughout the whole time that I've been using mobile phones, so obviously I've had to adjust to a few new things. One of these things is converting YouTube videos, mainly songs, to mp3 files online, and then downloading the converted file directly to the phone. On Android phones, this process was real simple. You copied the YT link of the song that you wanted into an online YT-mp3 converter, converted it, pressed download, and voila, the song was downloaded directly into your Google Play Music library, being able to be played offline whenever you wanted. However, I haven't been able to do this on the iPhone. I'm able to copy the link of the song I want, but when I press download and exit the inevitable pop-ups that appear, I get redirected to these weird online pages with sketchy links where the song starts playing. The song doesn't appear in my library, as a downloaded file, or anywhere in the phone. It simply appears and begins to play on this weird looking online page, and I'm not able to access it anywhere else. Does anyone know if there's a way around this, or a way to download the files directly into my library? It's really bugging me that Apple isn't a simple click and download like Android. Any help would be really appreciated.

P.S. no I can't transfer the mp3 files from my old phone through Bluetooth or USB