Unable to log in to iCloud on iPhone 3GS
I have an old iPhone 3GS, with iOS 6.1.6 installed. At some point months ago it was wiped but I don’t remember the process. I’ve just set it up as a new device, but can’t sign in to iCloud with it. It is connected to WiFi but has no SIM. If I enter my iCloud username and password on the 3GS it is recognised and I get the prompt on my newer iPhone to authorise or reject the 3GS. I accept it and get the 6 digit code on my newer iPhone but there is nowhere to type this code on the 3GS. I can’t work out where I’m going wrong, any help is appreciated!
iPhone 3GS, iOS 6.1.6