You did not mention your website URL on your secure note, I checked your Licenses page and there are lots of websites, that is why I am not sure which one you are talking about.
First of all, please consider that the file standard of the templates is completely different from the previous versions. So for example if you exported a page in an old version of the Pro, you can not add it to the new version as the Template Manager is completely different.
If you can not access the Design Cloud it shows that there is a firewall of some kind that prevents you to access our servers. This might be the same case as the problem of the Validation Connection that is why I suggest that you check that article troubleshooting steps.
Also, Test for a plugin conflict. You can do this by deactivating all third-party plugins, and see if the problem remains. If it's fixed, you'll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
These are the steps I could think of without having access to the WordPress Dashboard for your website. Kindly get back to us with the URL of your WordPress Dashboard and the steps to recreate the issue.