OLD IPAD REMOVE ACTIVATION LOCK

I have a ipad which was purchased on 21 Apr 2016 , I decided to purchase a new I pad pro 2021 and remove all my information from my old pad to my new, which has been done, I wanted to give this pad to my granddaughter to use during lockdown ,I arranged to get the old pad re installed use interface itunes which Exeter Apple store kindly done for me ,All good so far, however Activation Lock ask me to Enter the Apple ID AND PASSWORD THAT WAS USED SIX YEARS A GO in iCloud .com I cant remember setting up a iCloud account and have not used one, so I could not activate the I pad , the assistance acknowledge he new when the pad was purchase he was aware of other Apple items I have registered, But he could not assist me any further , so I contacted Apple support and told them of my problem who than sent me a link , on this link I had to supply documentation a receipt for the purchase and showing the serial number , Who keeps a purchase six years old when the guarantee has passed? I tried to get a copy from the company who the pad was purchased but they where unable to help me , I completed a form from Apple giving the serial number and a copy photo of the record Apple hold clearly shows they know when I purchase the old I pad and sold through channel GRO6 and showed the full product code and noted it is out of Warranty. I was also advise Apple know of my other Apple product and my email address I have always used ? Apple advised that the information they received from me was not sufficient for them to process my request to re- Activate my pad, But they have all the detail other than the original purchase receipt , I think they are asking for to much it is unreasonable to expect a person to hold a receipt for this length of time , it could have been lost over such a long period or missed place and because of there un reasonable demand a good ipad can not be used so it will be throw away , How unhelpful is this , any suggestions please Thanks