We got the same error.
Most likely it comes down to your corporate internet policies, as one of the ports are blocked.
Test if you can access Qliksense through a different connection (outside the company),
if you can then it means that your network administrator in your IT department needs to unblock certain ports.
I'm not sure which one it is but here's a list of the ports.
Ports ‒ Qlik Sense
We are also still struggling with this but this is what we are going try out first.
