Kept on getting the following message: Failed to start debug session. It's recommended to run project settings wizard and check installation of php and debugger..
Completed the wizard and no issues. Then, instead of step debug, I run, and find the page is not authorized. When doing the wizard, I provide the httpd username/password, but it doesn't stick.
My /etc/httpd/conf/httpd.conf virtual host includes the following.

AuthType Basic
AuthName "Restricted Content"
AuthUserFile /etc/httpd/.htpasswd
Require valid-user

How can I debug Apache password protected page?

Thanks

IDE can't "stick". What can stick is your browser. You can either use "save password" in your browser or use php session-based authentication, not Apache's one. In the first case you'd better switch to external browsers as the embedded ones have slightly limited functionality -- there is no standard menus and dialogs to manage saved passwords.