Tvheadend

Hardware - RPi Zero W, 64GB uSD card, RPi TV Hat. OS = Raspian Buster Sept 2019.

I've twice started with a cleanly flashed SD card, and installed TV Headend via "apt-get.." But I cannot seem to log in to complete the setup of TV Headend. I've tried both the Pi username/password combo, and that for TVHeadend without success. I'm on the network OK, and can use Putty to access the Pi interface. Now at a bit of a loss as to what I'm doing wrong. Looking for advice.

Thanks in advance.