I just bought a MAC and am trying to figure out the correct version of LR4 to install on the Mac. Someone in support (LR) gave the link for the downloads, and I chose the LR4.4 (but, it said LR5---kind of confusing). I don't have a DVD drive, so I am not sure if this one will work. I have the LR icon that says Light Room 4.4 on the screen, but LR does not open when I click it.....????? How do I open this? Thanks!!!