Hello everyone!
Facebook is currently having some issues. If you find yourself unable to log into the game on Facebook, you can do so via the Official Website or with the Mini-Client. To play on your Facebook account using the Mini-Client, you will currently need to bind a secondary/security email to the account first, which can be done in the User Center. You can reach the User Center by visiting

and in the top right, login using your Facebook account. You will then be able to click open the menu and access the User Center (As pictured).

Credit to Dresq for this answer, all verbiage his; thank you Dresq!