sudo flatpak install flathub org.mixxx.Mixxx
[sudo] password for nikolanp:

Note that the directories 

'/var/lib/flatpak/exports/share'
'/home/nikolanp/.local/share/flatpak/exports/share'

are not in the search path set by the XDG_DATA_DIRS environment variable, so
applications installed by Flatpak may not appear on your desktop until the
session is restarted.

Looking for matches…
ошибка: No remote refs found similar to ‘flathub’
nikolanp@comp-fx-6300-six-core-142a53 ~>