Thank you for feedback information and provided screenshot.
Kindly, give it some time to fully propagate to around the World as far as it didn’t existed before.
May I ask you to try using a different Web browser or a Private Window (Incognito Mode), or even a VPN connection (if possible), or at least if you have a mobile phone with mobile data (4G LTE, cellular data) you can try accessing your sub-domain with it, if so.
Nevertheless, maybe you might have to “flush” your DNS at your device, or the easiest way might be to restart your router. Otherwise, wait a bit more as it could be due to the ISP cache.
As far as I checked now, I see it’s working on my end.
Kindly, check the below screenshot and reply back if that’s what we expect to see?: