For simply management OS

sh -c 'echo "deb http://download.webmin.com/download/repository sarge contrib" > /etc/apt/sources.list.d/webmin.list'
###curl -sL http://www.webmin.com/jcameron-key.asc | sudo apt-key add -
curl -sL http://www.webmin.com/jcameron-key.asc | sudo gpg --no-default-keyring --keyring gnupg-ring:/etc/apt/trusted.gpg.d/webmin.gpg --import
chmod 644 /etc/apt/trusted.gpg.d/*
apt update 
apt install -y webmin

Edit webmin config

nano /etc/webmin/miniserv.conf

Setting port & disable ssl via change next

ssl=0
port=8000

Apply changes

systemctl restart webmin

Open firewall

sudo ufw allow 8000/tcp
sudo ufw reload

Open http://[Host_ip]:8000/ in your browser & log in with your system credentials – username & password.