I’ve only just setup my UniFi gear yesterday and am fairly new to HASS too.
I went to setup the Ubiquiti UniFi integration and it asks for a host, username and password.
Being such a n00b, I wasn’t sure what host it’s asking for?
Does it want the IP to our Dream Machine? Or… 
My setup: Ubiquiti Dream Machine, 24 port switch, two nanoHD APS, and 4 G4 cameras, and soon, the doorbell too.
Goal: Network Presence detection, G4 camera feeds in the dashboard.
Much appreciated.
For the cameras you’ll need the Unifi Protect integration, easiest to install through HACs.
For both integrations (Unifi Controller, Unifi Protect) you can set up a local administrator-level user account on the UDM and supply those credentials and the IP of your UDM in the configuration flow.
Ahh wonderful.
The bit that wasn’t clear was to go to http://unifi.ui.com/ and create a local admin user, and use those details (along with the local IP of the dream machine) as the details.
Worked a charm