Apple iPod touch 6 generation

I have a question, I bought second hand an Apple iPod 6 generation off an app called Mercari but the iPod has activation lock on it, I called Apple and they told me I needed their original purchase information and where they might have purchased it, I asked them but they don’t know, how do I go about getting the old Apple ID off the iPod so I can start using it?! Frustrated!

thank you in advance!

Michelle