Trouble logging into iCloud on 1st Gen iPad IOS 5.1.1

I have an OLD but very much so working first Gen iPad operating on IOS 5.1.1- I want to give it to my son as his first electronic device, but when I try to sign into my iCloud, it says I need to enter the two-factor authentication code, it sends it to my phone, but there’s no place to enter a code on the iPad... help?