how to enable directory browsing in Apache
From Sharkysoft Wiki
View your server configuration file and make sure that the directives for the folder you want to browse include
If you want to disable directory browsing for all locations but a few, then leave this option out of the main configuration file, and instead add it to an .htaccess file placed in the appropriate directory. Just make sure that you haven't precluded it in the main configuration file with an AllowOverride None directive.