Configuring CalDav and CardDav on Ubuntu Touch 20.04 OTA-5

[captainfuzzyface]

I have a Pixel 3A XL running UT 20.04 OTA-5. I have a NextCloud account which I want to use to sync Calendar and Contacts with (with other apps maybe later on).

I have the documentation at https://docs.ubports.com/en/latest/userguide/advanceduse/dav.html

and I'm using the 1. A simple guide proposed by Bastos77 and Vanyasem
I've filled in all of the variables as stated but I'm getting errors when I run the script through the adb shell.

The first one is...

[ERROR] creating source registry: The given address is empty

Could anyone offer help as to where I start with this.