Is there a default username and pwd to get new HA installation started?

Hi all,
I followed the intallation instructions using BalenaEtcher on a windows PC and installed:
https://github.com/home-assistant/operating-system/releases/download/5.11/hassos_rpi4-64-5.11.img.xz
on my SD card (32GB) for the Rasperry pi 4 (as instructed by HA website)
When I start my raspberry again I get finally a black screen with the following:

Welcome to Home Assistant
homeassistant login:

I couldn’t find any default user name or pwd. Is there one?
Does anyone have an idea how to get it started?
thanks in advance
a newbe (obviously)