What features does my canvas app need, in order to submit the application on the App Center?
Facebook gave me this response:
Ineligible Submission
Your app does not have high enough ratings and user engagement to be eligible for the App Center at this time.
Are you trying to get your App into Facebook App center? In your case, it seems that you don't have enough users to do so. Facebook review process states that "Once your app has enough high user ratings and engagement, you can be submit your App Details Page for App Center listing...", it means that you need to run your App for a while.
Per your question (but I don't think that that's your real issue), the eligibility requirements are (see the same link above):
Eligibility Requirements These apps are eligible for the App Center when they reach high user engagement and user ratings: A canvas page app with Login Dialog. A mobile apps built for iOS or Android and uses Facebook Login SDK for iOS or Facebook Login SDK for Android (More) A app that is a website and uses Facebook Login These apps are not currently eligible for App Center: A Page Tab app A Desktop web game off of Facebook.com