from the error message, it seems your ucs can’t reach our licence server. You can test it with the ping command below
ping -c 4 license.univention.de
else you might have to enter in an external DNS sever.
You can also follow your log file with the command below to see what happens while you send ping.
tail -f -n 0 /var/log/univention/management-console-*.log
Have a nice day.