Locate the Storage Account where your static web app was created. In the left menu, select Storage Explorer. Under then Blob Containers section, select $web. You'll see the files and you'll be able to download them.
the easy answer: give us a call or submit a ticket and we can look at your firewall to see what's going on.
the DIY answer: since you can reach "https://github.com" but not "https://rhui.rackspace.com", you might have outbound firewall rules configured, or servers at "rhui.rackspace.com" aren't behaving.
check your outbound ...