Cannot retrieve photos and music off of external hard drive onto 2014 Macbook Air

I have a 2014 Macbook Air. I previously had a 2011 MacBook Pro. I have a full backup of my Pro on an external hard drive. I am trying to move some music and photos over, but the laptop won't let me even open the files. I am receiving a message that tells me to download new versions of iPhoto and iTunes. I have done both and still no luck. Any suggestions?