Unable to sign in to iCloud on iPhone
Check your network settings, also go to iforgot.apple.com and enter your first and last name as well as the Apple ID email address to make sure that the account exists. If it does not identify it then it may be that you didn't verify your email address. If it does identify it then you may need to try restarting the device and the network connections to see if you are able to sign in (also sign in to the Apple ID page to verify that you can sign in after you have identified it as an Apple ID).