1.更新apt资源
sudo apt-get update
2.导入zammad仓库秘钥
wget -qO- https://dl.packager.io/srv/zammad/zammad/key | sudo apt-key add -
3.下载zammad仓库源
wget -O /etc/apt/sources.list.d/zammad.list https://dl.packager.io/srv/zammad/zammad/stable/installer/ubuntu/18.04.repo
4.安装zammad，等待安装完成
apt-get install zammad