Why is a log-in prompt message indicating no account has been registered, although the account has been registered?

🟠 The following reasons may lead to the error prompt. Please check them one by one:

(1) Please confirm whether to select the corresponding country.

(2) Please make sure the account and password you entered are correct.

(3) Spelling error. Please ensure your account and password are spelled correctly. A misspelling may result in an account that doesn't exist.