Comment 6 for bug 1426920

This window shows during the installation process, almost at the beginning, right after a slide with available Wi-Fi network shows up. I think it's right before the screen when you choose to download or not the updates during the install and to enable or not third party software.

When I choose my home WiFi network from the list and click "Connect" (far bottom-right button, like "Next"), then this Wi-Fi Network Authentication window shows up (as a smaller one, in front of the main installation).