I picked it because it's in a language I know (Python) and free and copyleft. These days I don't contribute to anything unless it's copyleft.
No idea if it supports family calendar, I need to look into that as well at some point.
EDIT Just checked and supports auth, yes.
It used to be a constant headache to keep running, but ever since I switched to the TrueNAS/Docker plugin it has worked smoothly. I know a lot of other people also have had good luck with the much lighter Radicale if CalDAV is your primary concern.
It’s been very easy to run for me since version 15 or something. Basically i just use the stock docker image and mount a few files over there. The data folders are bind-mounded directories.
As usual with anything php, it’s only a mess if you start managing php files and folders yourself. Php has a special capability of making these kind of things messy, i don’t know why.