Your statement about compatibility with IOS 10.10 did not match my experience. I have a new Macbook Pro (10.10.1) and can't download the 30-day trial for Lightroom. I followed all the steps 3 times. I created an account but can't download.
(Getting tired of signing in over and over)
I'm using Safari. Nothing happens. I click the button that says it should start immediately, click here if it doesn't. Still nothing. I search to see if it downloaded in the background. Nothing.