I am a fully paid up member Adobe cloud and logged in. Other pages of the Adobe website are all accessible except the Lightroom download page. I have tried a few times over the last few days taking different routes to the download page including direct from the notification in the app but no success
Launch Creative Cloud and click the settings gear icon.
Try signing out and then signing-in again from preferences.
Wait for CC to update if necessary and then go to the Apps Tab
An install button should be available for LR CC 2015