I feel dumb just asking this as it should be simple/obvious.
I want to share my work zimbra calendar with my home zimbra installation. I can do this by sharing the calendar publicly and then adding a new calendar to the home account and pointing it at h_ttps://workmail.zimbra.com:443/home/myusername/Calendar and that works just fine.
I dont want public access though, so I pick external when adding the share and give it my home email address and a made up password. Then visiting the above link in a browser results in a username/password prompt, and keying in those credentials works.
So, how to add this to the home zimbra? There's nowhere to provide credentials and I've tried every permutation that I can think of to put them in the URL.