How can I remove Activation Lock on an older iPad? Email has been deactivated.

So my mother-in-law has given me her old iPad for me to use for teaching, but the problem is that she cannot remember the iCloud account password. I tried to reset the password but the iCloud is linked to an old email with AOL email that is deactivated and I called AOl and they said I would have to pay money to reactivate the email. I called apple to ask if they could reset the password, but they can't have the information sent to a new email and in order to restore the iPad I would have to show proof of purchase. This iPad was purchased 10 years ago and we for sure don't have that information. Apple said they don't have this information either since it was more than 6 years ago it is now considered 'obsolete' and the information for purchase has been deleted. I really need to be able to download apps to use this iPad, but right now it is literally sitting useless. Does anyone know what I can do to get it working again??

[Re-Titled by Moderator]