Changing the Apple ID on a 1st generation iPad

We are trying to add apps to our 1st generation iPad. We reset to factory settings and need to add some apps to it. I tried signing in with the same Apple ID that is on our other iPad and my husbands iPhone. It says that I need to reenter the password and add a verification code that is found on our other devices. However, when we try to sign in again, it never gives us the option to enter the verification code so we have been unable to download any apps leaving this iPad virtually useless. All the apps require iOS 9 or higher and this generation's highest available version is iOS 5 so we can't download directly. I need to be able to change the Apple ID on the iPad so we can share apps between our devices.

The old iPad doesn't know about verification codes so doesn't know how to ask for it properly. You can still sign in by adding the verification code to the end of your usual password in the normal password box when trying to log in.