According to Appleinsider, an unknown problem occurred in the back end of Apple’s iCloud, which seems to have caused new device installation and account activation failures.
The Apple system status page shows that an unknown problem occurred with the iCloud account and login service at 5:45 pm yesterday. Some users are affected, and users may encounter problems when using this service.
Many users who received iPhone, Apple Watch, and HomePod as Christmas gifts have reported device activation problems on Twitter. Some users take a long time to create iCloud accounts and install new devices, while others cannot create them at all.
Apple Support discovered this problem on Twitter and said, “We are currently under high load, which affects your experience of setting up iCloud. Please try again in a few hours.”
(via)