I use CityEngine v. 17 .1.
I have a valid ArcGiS account, but I can't sign in to ArcGiS online in CityEngine.
Portal https://www.arcgis.com is "Not available"
when I change it to http://www.arcgis.com it becomes available, and the signup dialog box appears
but it throws :
"Unable to connect to ArcGIS Online or Portal with given username/password"
My institution has a floating licence on Cityengine.
What's wrong and what can I do about it ?
Did you figure out what was happening?
If not, try inspecting the http traffic with fiddler
In our case, the company proxy had to be configured correctly.
See this thread for more details: