Q: How do i get itunes on an Android 5.1.1

Do you mean how can you get an app called iTunes on your Android? If so, you can't. You can, however, download the Apple Music app from the Google Play Store.

Or, do you mean, how can you get music that you purchased from the iTunes Store onto your Android? You'd transfer it in whatever way you generally transfer music to your phone. Drag and drop usually works fine.