Trying to find ID on a website?

Hi there. I’m selling on a third party site, trying get access to email addresses of customers that purchased from me. I have their customer id, but not their user id. If I can get their “user id” (It’s a really long token), I’ll be able to use both ID’s in a URL and access their email address. If you can figure out how to get this “User ID “and teach me how to do this, I’ll pay $150 USD for your help. DM me for more info.

Thanks