The solution I linked is basically the same as the one on that site and it didn’t work to me.
The link format isn’t working either.
I tried that link format. It doesn’t give me an error message at least. But it stuck at “creating account”.
@usbee Did you manage to get CalDAV / CardDAV working eventually? I succeeded in configuring CalDAV (calendar) but CardDAV (contacts) gives me an headache. I tried contacts.icloud.com and the solution provided by @nephros combined with an app-specific password for iCloud but not success. Authentication fails because of a /.well-known issue.
Can’t figure out if I’m doing something wrong or it is an issue with the CardDAV implementation of Sailfish. CardDAV / CalDAV implementation of iCloud is not documented at all by Apple.