Trying to get an ipod 3rd generation to connect to icloud

Trying to get an ipod 3rd generation (5.1.1) to connect to icloud, in order to have it seen on "Find My iphone" apps on current devices (ie IOS 16.5). I have two of these ipod devices. One I've had since it was first released. This one can be seen just fine on the Find My apps. The second one, recently acquired, I cannot login with my AppleID. I can access the app store using the technique of entering password followed immediately by the security code send my apple. However trying login in to icloud or "Find iphone" app on the ipod is unsuccessful. Sometime it asked for the recovery code, however I never set one up. In any case it expects a 12 character code and it is my understanding that setting up a new recovery code will provide a 28 character code. Any ideas on how to proceed? Thanks.