Search Appliance
The Search Appliance itself needs read access to the entire set of URLs in order to build a search index. Therefore, before walking a protected data set for Results Authorization, it may be necessary to fill out the Login Info setting (here) under All Walk Settings with a full-access admin type account, so that the Search Appliance can walk the data.
Or it may be necessary to fill out a Primer URL (here) containing login info to submit to a site's login form, so that the Search Appliance can obtain the login cookies needed for access to the rest of the site.