This almost always means you entered your regular Google account password instead of an App Password. These are two different things — and GetReplies requires an App Password.
What is an App Password?
An App Password is a 16-character code that Google generates for third-party apps that connect directly to your mailbox.
How to create an App password?
Refer this article to create App Password: https://support.google.com/accounts/answer/185833