Unable to connect

After purchasing / downloading / using Sketchup Pro for a week I was away for 2 weeks. When I returned and tried to use SketchUp I received the “unable to connect” even though my internet connection is live! I downloaded and restarted Sketchup Pro, but got the same error. I can access my Trimble account via Safari. I also have Google Chrome on my 'puter. I did not change any settings. Can someone walk recommend a fix?
Thanks!
Michael

The installing part is missing, don’t run from the downloaded ‘disc-image’ directly.