User name and passwords

I don't know anything about DAVical, but Date iCal doesn't directly support CalDAV. It's on our long-term TODO list, though.

To require a username and password for the calendar, the first thing that comes to mind would be to apply a permissions limitation on the View that's serving the iCal feed. That way only users with the right permissions would be able to see it.

I have same issue for User name and passwords when I try to use Outlook adding ics file from Views Calendar.
The Outlook ask me Username and Password (or Domain name).
I try Drupal site user name and password, and my computer's username & password. But it doesn't work. So I can't import ics file.
Which user name and password should I input?
Any help would be appreciated.

Have you tried downloading the .ics file directly from your browser? I don't know anything about why Outlook would ask for a username and password, but we can rule out Drupal and Date iCal if you're able to download the .ics file from a browser.

Thank you for your reply.
It is work when I download .ics file and import it.
Thank you very much.