Hi
Please go through the the article mentioned below :-
By default, AEM now prevents read access for anonymous users to certain locations in the repository on a publish server. If the site requests resources in these locations, they will not be loaded and result in a 404 error. We recommend moving these resources to publicly available locations in the repository.
An anonymous web site visitor has no access to following paths in AEM 5.6 or later:
It is recommended to place publicly accessible resources in:
Link:- https://docs.adobe.com/docs/en/cq/5-6-1/deploying/upgrading/tips-and-troubleshooting.html
And there is a community question analogous to you problem:-
Link:- http://help-forums.adobe.com/content/adobeforums/en/experience-manager-forum/adobe-experience-manager.topic.html/forum__v7sy-hi_all_i_havecr.html
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Modify the configuration of Apache Sling Authentication Service.
Add an entry in sling.auth.requirements parameter.
If you want anonymous access, you have to put a '-' before the path.
I hope this would help you.
Thanks and Regards
Kautuk Sahni