Beats 1 and Mountain Lion Why does Apple require an update to OS X 10.9 to access Beats 1? I have iTunes 12.2 installed, I can see Beats 1 in my iTunes app, I can even stream Beats 1 by manually opening its URL in iTunes. So why won't iTunes just let me listen to Beats 1 on Mountain Lion? As far as I can tell, there are zero technical reasons for why I'm having this problem. Anyone?
Due to the fact that Apple provides upgrades and fresh installations of their operating systems for free, they would (in most cases) only provide support for the latest operating system and (in many cases) the one before it (in today's case (as of the time of this answer), OS X Yosemite and OS X Mavericks respectfully). If there is something wrong with iTunes, Apple would usually recommend that you upgrade to the latest version of OS X.

In your case, iTunes requires OS X 10.7.5 (Lion) or later, but Apple Music requires OS X 10.9.5 (Mavericks) or later (source: http://www.apple.com/itunes/download/; under "Software"; look at the screenshot below) also, look at the ), so chances are it will not work unless you upgrade to at least OS X Mavericks.