Interestingly the "Try Now" opens iTunes which in turn asks you to upgrade iTunes which in turn leads you to a site asking you to download the old 12.1 - Bit of a hick-up there.
hiccup.
:)
hiccup!
Same problem here. Pretty odd not to support your main desktop OS at launch.
OS X just updated to 10.10.4, available now & free.
I just updated to 10.10.4 but it doesn't update iTunes to 12.2, the version required for Apple Music. Guess it'll be out later today.