wget https://repo.zabbix.com/zabbix/5.0/ubuntu/pool/main/z/zabbix-release/zabbix-release_5.0-1%2Bbionic_all.deb dpkg -i zabbix-release_5.0-1+bionic_all.deb apt update apt install zabbix-agent
in install press N for keeping old config or Y for install new config file
if Yes - edit conf & restart zabbix agent
nano /etc/zabbix/zabbix_agentd.conf # add server passive IP, server active IP, hostname systemctl restart zabbix-agent.service