version 10.13.99 is not a real standalone version of iTunes.
Since version 12.10.13 is not directly listed on Apple's main site, here are the most reliable methods to get the latest compatible version for your system. download itunes 101399 for mac free
iTunes 12.6.5.3 was designed for older versions of macOS. According to Apple's specifications, it officially runs on: version 10
Before attempting to install this specific vintage version of iTunes, check your Mac’s current operating system. Older versions of iTunes have strict software and architecture requirements. Operating System Compatibility download itunes 101399 for mac free