There has been an ongoing issue with Apple’s iCloud Account and Sign In service, affecting a large number of users but not everyone. The “System Status” page indicates that the problem started yesterday morning, and at the time of writing it, it’s still ongoing and unresolved. Naturally, there’s a flood of user reports on social media and forums where people seek a way to get around the log in issue that cripples their devices' functionality.
Apple has confirmed the problem and attributed it to “high capacity”, probably meaning that they’re dealing with much larger traffic than what they are able to handle. Until this is fixed from their side, the official instruction is to try again in a couple of hours, which could infuriate those who just bought a device and look to set it up. Obviously, there must have been a sudden surge from all the new Apple devices opened as Christmas gifts.
That would include iPads, iPhones, Apple Watches, HomePods, etc. If you unboxed one of those yesterday and you’re stuck in the “configuration” screen, don’t waste your time rebooting/resetting and trying again. Just allow a couple of days for the influx to wane, and you should be good to go. Unfortunately, there's no workaround for this problem.
Many people wanted to enjoy their devices now that they have free time to fiddle with them. It’s annoying, to say the least, and Apple should have known better and be prepared for the sudden rush of device activations, but unfortunately, this is the situation right now.
Even if you manage to activate your new device, you may still experience problems with the iCloud service, partial syncing of data, or sudden outages. Again, this is not a problem with your device, but a server overload on Apple’s side. If you still want to contact support for some form of assurance, you may do so through this web page.