Problems setting up CardDAV in OS X Server

I'm trying to set up a mini to act as a server so that I can sync Contacts and Calendars between my Mac and my iPhone. I've been following the instructions at http://securityspread.com/2013/10/27/setting-sync-server/ but I am stuck because I can't create a CardDAV. When I try, I get “A secure connection couldn’t be established” alternating with “Unable to verify account name or password”, no matter whether I try upper case or lower case for the user name.

I'm trying to do this on Mini.local – I saw in https://discussions.apple.com/thread/5660157?answerId=24113854022#24113854022 that MrHoffman recommends against using .local though I am not sure I follow what the alternative is. I have my own domain; I could create sync.mydomain.com or something but I am not entirely sure how that would work.

Or if that would be the solution to the main problem, which is "I can't create a CardDAV".