Setting up iPad

This is what you can do:

See If you forgot your Apple ID password https://support.apple.com/en-us/HT201487

You also can use Having trouble signing in/iForgot  https://iforgot.apple.com/password/verify/appleid 

You also are likely to need to See If you forgot the answers to your Apple ID security questions https://support.apple.com/en-us/HT201485

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Note that if you are you are unable answer your security questions satisfactorily, we can do nothing to help you, except to mention that Apple support might help you if you have an extenuating circumstance (e.g., you have the receipt for your purchase of a pertinent device with its serial number on it). if you want to contact Apple support to discuss any possible extenuating circumstance, see these support options:

Get a call from Apple support to help solve your problem using this

link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362

Apple ID Support https://support.apple.com/apple-id

Apple ID account security for country-specific and region-specific help https://support.apple.com/en-us/HT204169

Get Support: We’re here to help https://getsupport.apple.com/. Go through the options to find the best support option.

He can try the various email addresses he has access to.

See if you can recover the ID/password.

Apple ID - How to find your Apple    An iCloud e-mail address is an Apple ID.

Apple ID - Find