Email and Password Login has been depreciated. If you have yet to link your Discord to your account but are still logged in, you may link your account by clicking [Your Name] > Account Settings > Discord.
Otherwise please contact administration for assistance.
You will be allowed to use an email and password to create an account but you must link your discord account to login. When creating an account just use the Discord Login Button on the sidebar to create a new account with your Discord account.