Why is this happening to my app?

Well my sister and I got the iPhone 6 and the people from the store said that they couldn't save our apps so that meant that I was gonna lose all my music because I had it all in one app but they did say they can save my pictures so I screen shot all of my songs and I was planning to download them all again on an app but all the music apps on the App Store suck I mean when you search for a song all of the apps show the same result and it's mostly covers or it has the song but not the full version so my sister told me about this app called idownloads plus and she could download songs on that app but when I would try it it wouldn't work so I don't know what to do now. Is there a reason why this is happening? Is there a way to fix this? Or is there any music apps where you can go to the browser and go to the music website to download the songs?

You could try Spotify? They have full versions of songs and it works just like apple's music app. You can make playlists and listen to radio stations for a certain band/artist/genre of music. Although they offer a free membership trial it ends after a week or so… But you can still listen to your music for free but there's just gonna be ads and you can't skip:/ I don't know the app you're talking about but hopefully this helped? You could also download songs from youtube. If you don't know how there's plenty of easy youtube tutorials explaining how to