@noise
I think you might have a few things backwards here. First of all the depreciation warning itself is harmless, as it is a warning, not an error. So whilst it would be nice for a developer at Kopano to look at this, it won’t stop kdav from working.
A few other observations:
You are running composer install as root, which, as the console output tells you, you shouldn’t be doing. Instead, change to your webserver user and run composer with that.
su nginx -s /bin/bash
cd /var/www/kdav
./composer update
./composer install
I am adding the composer update command because of the output you see in the terminal. I personally have never used that.
The php dav extension you are installing in the beginning is unnecessary as composer downloads all dependencies to the kdav folder. You can hence skip that.
I myself am still struggling to get kdav working (again), so I’ll post back in case I succeed.
