What is your default browser? The authentication page looks like it's from internet explorer.
You can also double check if the firewall is not blocking outbound and inbound traffic for store.thinkwisesoftware.com
Hope this helps!
Chrome is my default browser. Though I have Firefox and Edge too. It looks like the SF starts this pop-up in internet explorer.
When I go to https://store.thinkwisesoftware.com/ manually in my browser, I get access to the login page. After logging in I get the same error. So it looks like the same problem as what is happening in the SF. Since I can access this page it seems not to be a firewall problem.
In Firefox, after logging in you get the to the same problem, same in Chrome