Using the same Adobe ID, I have an iMac and a MacBook Pro on Photoshop CC/Lightroom CC and a separate iMac on Lightroom 5. I purchased an upgrade for the iMac with Lightroom 5 to go to Lightroom 6. After dowbnloading and "installing" the upgrade, when I try to sign in I get a "Sign In Failure" (before I can use the activate code to prove I purchased an upgrade), telling me that I already have two computers activated with Lightroom 6 activated and can't have a third one. It obviously doesn't differentiate between my Lightroom CC subscription and my Lightroom 6 Upgrade purchase. What can I do to install an upgrade from Lightroom 5 to Lightroom 6 on my iMac?