icloud recovery key

I just got a new Iphone and a newer ipad. I also have a desktop iMac and a older ipad.. when i try to go and do a backup to icloud,( which has cost me .99 a month for years) on the old ipad it requests a recovery key.. I bought the old ipad in 2008 i believe.. i do not remember ever having a recovery key and have done my best to look in the old paper work to see if i can find a number, i do keep pretty good records and have had no luck... After reading this page for community support, i have repeatedly signed into the Apple Id page. While i see a place to change passwords, i can find no recovery key change button under security or any other area.... i even tried what i thought was a good idea, to put in my password and the (one of many) current verification codes i have been receiving.. it will not accept letters and no more than maybe 7-8 spaces for numbers.. Thank you for your effort to help... but not all of us have an access to a "create a new recovery key" option.. the older ipad says recovery key needed if you do not have access to a password or a trusted device.. which i have both.. I have to use the password to get to the place to enter the recovery key.. after receiving the verification code.. i' stumped..