Activation Lock on my old iPad

Today, I was transferring photos from my very old iPad (16 prong), which I haven’t used in a very long time. Inexplicably, the iPad went blank then came back on with the apple symbol. When the symbol cleared “Activation Required” came up. I cannot remember what information I put in or my old Apple account information. It will not open using my current account. I’ve looked everywhere for my old information and cannot find it. What can I do?