If you are running macOS Catalina, Big Sur, Monterey, Ventura, or Sonoma, you generally cannot install old versions of iTunes. The operating system architecture has changed fundamentally, and iTunes is no longer a single file but a system service split into three apps.
Apple has officially discontinued iTunes for Mac as of macOS Catalina (10.15). Modern macOS versions use Finder for syncing. However, version 10.13.99 (often mis-typed as 101399) refers to a late-stage release of iTunes 10, which is roughly a decade old.