Why does it keep saying 'Adobe Application Manager is needed to resolve this problem'?

I have been unsuccessfully trying to set up CC on my new iMac - I have downloaded desktop CC, but cannot see any of my apps - it says 'download error - download Creative Cloud'. So I quit out, download Creative Cloud again...and then repeatedly get the error. 'Adobe Application Manager is needed to resolve this problem. However it is missing or damaged. Please download and install a new copy of the Application Manager from etc etc...'. I do this, but it makes no difference and I keep getting the same messages. I'm getting really angry about this, it should be easy, and I have work to do! Can anyone help please? Thanks!