Installing a snap on Ubuntu is as easy as:
sudo snap install rocketchat-server
sudo snap set rocketchat-server caddy-url=https://chat.rsudpbari.com
sudo snap set rocketchat-server caddy=enable
sudo snap set rocketchat-server https=enable
sudo rocketchat-server.initcaddy
sudo systemctl restart snap.rocketchat-server.rocketchat-server.service
sudo systemctl restart snap.rocketchat-server.rocketchat-caddy.service