Best music downloader for macbook and iphone 6plus?

Obviously I know that everyone can not afford to buy songs off of itunes for $1.29/pop. That's just insane. Right now I am using the website vid2mp3.com to get music onto my itunes. But I am mainly wondering if there is a good music downloader app that will let you download as much music as you want and store it on your iphone for you. Please help me out, I have not been able to find any good apps, and have been struggling with this a lot! And also sometimes my apple music app will have music on it that I didn't even put on there. How do I fix this? Any help, tips, and advice would be greatly appreciated, thank you!

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