The most likely answer is that we were not able to automatically confirm your age or state of residence. You must be at least 21 years of age and a resident of one of our approved states in order to be approved for an account. For your security, we use third-party systems to verify the information you submit during sign up. If those systems cannot verify your information, we may need to manually review additional documentation such as a Drivers License or State Identification card.
There are other reasons your application may have been declined. For instance, we do not allow duplicate accounts. If you already have an account, you can't open a second one.