I have the aforementioned Z1 card and it works juts fine in Ubuntu 18.04
under pulseaudio. But not via ALSA. Here are some details:
boris@cencerro:~$ aplay -L
default
Playback/recording through the PulseAudio sound server
sysdefault:CARD=Z1
Traktor Kontrol Z1, USB
Hi,
actually the pulseaudio sound server does use the ALSA driver to get
access to the audio interface. If pulseaudio has already grabbed the
audio interface via the ALSA driver, you first need to disable
pulseaudio, before other software can access the hardware
by the ALSA driver.
I can't help