Cannot sign into App Store it keeps asking for an email.

I have had my apple account forever and my iTunes / App account isn't associated with an email, but a user name. I have an apple email as well but I don't use it for the App Store. This has worked for years and I got a new iPad yesterday and I cannot sign into the App Store. It asks me for an email and password - and that works with me using my user name- it even sends me a verification email, but after that it asks me for an email to connect it with - and since I've never done that before I gave it my iCloud email and it won't accept it. I have a ton of apps connected to this method and do not want to re-purchase. What's a solution?

thanks