Hello Sanjeev,
I think its a common misconception to expect that service will be accessible anonymously because the text says "Required with Logon data".
By making this setting, you are infact instructing the server to allow login only if the userid/password matches the logon data that you have supplied in the configuration, in other words, the userid/password would be requested regardless.
This is explained in the documentation here.
To carry out activities that you are trying to do, I would suggest that you read and understand Authentication concepts here.
The above documentation will help you understand what you need for your scenario.
You may need to implement SSO configuration as suggested in the documentation, which one will depend on your requirement.
Regards,
Siddhesh