Error validating access token: The session has been invalidated because the user changed their password or Facebook has changed the session for security reasons

Hello all, I bought a script that does an auto post to facebook groups and pages from the following link [login to view URL] Schedule posts are not working. Instead, it is showing an error in the logs. "Error validating access token: The session has been invalidated because the user changed their password or Facebook has changed the session for security reasons." Can anyone help with this? Thank you!