$ sudo su
[...]
# URL=https://serial:<I>License_Key<I>@download.kopano.io/supported/meet:/final/Ubuntu_18.04/
# echo "deb $URL /">> /etc/apt/sources.list.d/kopano-meet.list
# curl $URL/Release.key | apt-key add -
# apt update
# apt install kopano-meet-packages
# exit
### Alternative
$ sudo apt install kopano-meet kopano-kapid kopano-grapi-bin kopano-kwmserverd