Install impossible

[frankenstein91]

Unfortunately, I fail to install it according to the instructions on the website

sudo bash /tmp/feed.sh
Clone to '/usr/local/share/airplanes/git'...
remote: Enumerating objects: 17, done.
remote: Counting objects: 100% (17/17), done.
remote: Compressing objects: 100% (16/16), done.
remote: Total 17 (delta 2), reused 6 (delta 1), pack-reused 0 (from 0)
Empfange Objekte: 100% (17/17), 15.41 KiB | 751.00 KiB/s, fertig.
/usr/local/share/airplanes/git/configure.sh: Zeile 109: hostname: Command not found.
remote: Total 0 (delta 0), reused 0 (delta 0), pack-reused 0 (from 0)
from https://github.com/airplanes-live/feed
 * branch            main       -> FETCH_HEAD
/usr/local/share/airplanes/git/update.sh: Zeile 164: adduser: Command not found.
/usr/local/share/airplanes/git/update.sh: Zeile 164: adduser: Command not found.
------------
[ERROR] Error in line 164 when executing: adduser --system --home-dir "$IPATH" --no-create-home "$UNAME"