Du kannst iTunes 12.6.4 über die neuere Version installieren - laut Apple:
Deploy apps in a business environment with iTunes:
https://support.apple.com/en-us/HT208079
"If you've already installed a newer version of iTunes, you can download this version of iTunes on your Mac ... and run the installer."
https://support.apple.com/en-us/HT208079
"If you've already installed a newer version of iTunes, you can download this version of iTunes on your Mac ... and run the installer."