If you still see the same error please try to login in your cell phone or from different network environment such as from home.
We cannot reproduce this in-house but some of customers see this issue and a few customers resolved it'
Below are the reply from those customers:
We were able to fix the issue by changing trust policies specifically for acrobat.com on our network. As far as I know they just whitelisted acrobat.com. Like put an exception in the firewall for that site.
I discovered that there was a blockage in my corporate network. The firewall was blocking my access to cloud.acrobat.com