First, to log in to your account, you must use correct login link:
The page that opens is also your "server address" when setting up Seafile drive/client/app in order to sync your files with your devices.
Second, make sure you don't write your password/email address with extra spaces or symbols.
Third, make sure you type the same password as you wrote when signing up. (This happens more often than one would think).
Fourth, try a different browser & clean your cookies + browser cache. Sometimes other passwords get cached in the browser...
If any of these tips don't work, please contact our firstname.lastname@example.org