If it is just asking for the number, do you remember the number? It may not necessarily even need to be active, it just wants the number.
If you don't remember the number, are there options in smaller letters below the main request? Have you tried those? Keep trying options.
If eventually you find you can’t sign in, reset your password, or receive verification codes, you can request account recovery (read this support article: How to use account recovery when you can’t reset your Apple ID password - Apple Support ) to regain access to your account. Account recovery might take a few days or longer, depending on the specific account information you can provide to verify your identity.