download iTunes on Mac mini

If your Mac mini is running macOS 12 Monterey, you cannot download iTunes to it, but you also don't need it.

All iTunes functions still exist on macOS 12, but are separated into the Music, TV, Books apps and the Finder.

What do you need iTunes for specifically?

iTunes has been replace by three apps, Music, Podcast and TV apps. YOu now uses (even before Monterey) the appropriate app instead of iTunes.

You use the Finder for that now. See here: link-> Use the Finder to sync your iPhone, iPad, or iPod with your computer - Apple Support