wget http://repo.zabbix.com/zabbix/3.0/ubuntu/pool/main/z/zabbix-release/zabbix-release_3.0-1+trusty_all.deb
dpkg -i zabbix-release_3.0-1+trusty_all.deb
apt-get update
apt-get install zabbix-server-pgsql zabbix-frontend-php
create database zabbix;
zcat /usr/share/doc/zabbix-server-pgsql-3.0.*/create.sql.gz | psql zabbix
CREATE USER zabbix WITH PASSWORD 'aaa';
GRANT ALL PRIVILEGES ON DATABASE zabbix to zabbix;

Added password here /etc/zabbix/zabbix_server.conf
Add timezone here /etc/zabbix/apache.conf

service zabbix-server start
service apache2 restart

Go to http://server_ip/zabbix and get this (see attachment) - No Postgres only MySQL

I have installed postgres 9.4 but zabbix installed 9.6, so i remove 9.4 with apt, so it should not affect.