When trying to log in to AEM, the error "User name and password do not match" is returned in a red box on the login screen.
When inspecting the network traffic via a browser debugger, a 403 error response is returned from an Ajax HTTP POST request to this URL:
The user name or password could be incorrect or there could be an error from the authentication handler during login.
If the issue only happens with one or a few users, then it could be that the wrong user names or passwords are being used or the users don't exist in AEM.
If any errors or warnings are logged, then analyze those warnings. If nothing is logged, then enable a debug log with these settings:
Log Level: Debug
Log File: auth-debug.log