My previous issue with LDAP authentication has been resolved, largely thanks to tmontagne's assistance. Info on that can be found at the Use Cases for LDAP page.
The current problem is that when an LDAP group is mapped to an XWiki group, the privileges don't seem to be set properly for users of that group. I am able to log in as a test user, and no matter the privileges I set, the user is unable to view any pages! The user is show as being in the correct group in the XWiki Groups UI, and the group has the proper privileges in the Access Rights UI. I'm not sure whether this is a configuration issue on my part, or an issue with XWiki itself.
Note that if I map an LDAP group to a pre-existing XWiki group, such as XWiki.XWikiAdminGroup, then the user is able to log in, view pages, and even administrate the XWiki properly. The issue seems to be with groups that I have created.