problems updating Lightroom from Creative Cloud desktop app

I have copied my Lightroom catalog from my old iMac to my laptop, and the older version of LR on the laptop won't read it. Error message reads:

The Lightroom cataog named "...." cannot be opened because it is too new to be used by this version of Lightroom. Would you like to select a different catalog?

So I guess I need to update my laptop version of LR. However, from the Creative Cloud destop app, it offers an update, but fails immediately with the following message:

Update Failed

The download appears corrupted. Please try to download again.(U43M1D2015)

Error code: 205

I have tried again and again over the last 12 hours. Same result. I have 65Gb spave on my HD, and obviously my OS is up to scratch otherwise CC wouldn't permit the update. What's wrong?