I have had *mixed* success with this on mobile devices. I can't recall if Windows 7 worked or not. In my initial testing after put in Extreme AP's, the mobile devices (I tested three) all of them went to the sign-in page almost immediately after joining the guest network. But I have had some reports that my guest network "doesn't work" and it's usually because the phone didn't prompt them to go to the sign in page.
When the magic fails - if you open a web browser on the device, it will redirect you. But if you open an app on a phone, the app just doesn't work.
I don't know that this is something that Extreme can really do better, because it seems that the mobile device is at fault here. What SHOULD happen, is that when you join a new network the device will request a specific URL from one of many IP addresses. The page is usually something to the effect of "generate_404". And if it gets anything other than a simple 404 message back, then it should tell the user that they need to sign in. I have done some sniffing, and I can watch a device try the 404, and fail, and yet *still* not prompt the user to sign into the network. WHY?!?!?!
I also have a theory that this whole
"Wi-Fi Sense" system is screwing things up. I went from a network that requires no sign-in, to one that does, and I never changed the SSID. That was probably a bonehead mistake on my part, because public devices may have (?) already been talking about my network and "crowdsourcing" the non-sign-in detaul. BUT --- you said Windows 7 and this seems to be introduced into Windows 10.
Anyhow - I would love some community feedback here. I am curious to know what others experiences have been with this.