If you enter the wrong email or username more than 4 times, you can't try it again for 10 minutes. If you're not sure, reset your password. Also, look in your Spam and Trash folders in your email for messages.
CAPTCHA is invisible and is dependent on the strength of your password and if the input is Human or Bot generated.
Create strong passwords from the start. A new strong password can be made up of the following recomendations.
At least 12 characters.
At least one of each: uppercase letters, lowercase letters, numbers, symbols.
No character may be repeated 3 or more times.
No ordered numeric sequence of more than 2 characters is allowed (i.e. 123 or 321).
No ordered or patterned sequence of adjacent characters of more than 3 characters (i.e. abcd, abab).