That error has nothing to do with the ITL file, that is an authentication probelm with the iTunes Store, which says that you've still got iTunes 11 remnants on your system.
Did you use Pacifist to install iTunes? If not, we can't be sure that iTunes is correctly installed. Mount the iTunes DMG file in Finder, open Pacifist and then drag the iTunes PKG file onto the Pacifist main window. That opens up new window. Click on the top-level part of the package and then click on Install in the window frame above.
You'll be presented with a dialogue box that offers yout o run with admin privileges. You must make sure that checkbox is ticked; otherwise, you will not overwrite the required files on the OS. Remember: Installing into the system's Application's folder requires elevated privileges, and iTunes runs deep into the OS with various bits and pieces outside the Applications folder.
For each dialogue box that opens regarding a particular file or type, be sure to check the don't ask again checkbox and then Yes. This will streamline the installation process, as we want to overwrite ALL files.