Message asking me to download iTunes Store when i select this option

I am trying to purchase music from iTunes but when i tap on the option to purchase music in itunes i get the message that asks me to download it but i want to purchase it all it wants me to do is install it from app store and i don't know how to purchase music with this message popping up when i select "open itunes store & purchase". What do i do if this message comes up? Dp i not have iTunes?

it asks me to restore "itunes store". What does that mean?