Hi I am posting this in case someone in the future ends up here. I faced the same issue. In the Chrome console, I could see 503 errors (service unavailable). I tried most solutions posted online (appending verification code, using another device, logging to to iCloud then App Connect) but all failed for me. After around 5 hours, I tried again, but this time it was on a different network (same device and browser). And it let me sign in ( however, it asked for a verification code from my iOS device).