Raspberry Pi Buildbot .iso

Well, downloaded the build, used the rpi imager_1.4 and created a bootable sd.
and it works!!! boots up clean and pretty.
Now, I'd like to play with it, but sudo wants a password..........
The username is 'linuxcnc'
Little help here, please.
What's the associated password?
tried 'root' and 'raspberry', no success........

ok, apparently the 'linuxcnc' user password is 'tux'
still no idea what the 'root' password is............

ok, more effort.
did a sudo su into superuser, the used the regular password change to set 'root' password to 'tux', same as user 'linuxcnc'
seem so be ok.