Hello,
This article guides you to:
1. install bitcoin from source
2. allow bitcoin on ufw
3. setup cron to start bitcoin on reboot
The instructions for installing from source are good.
The instructions for ufw are good if you are using ufw. This is a popular firewall for Ubuntu. If you are running a different distribution, you may have another firewall. This is why I suggested that you find an article for your distribution.
Also note that your hosting provider might be running firewalls around their network too that block access to your wallet’s RPC port.
The cron trick is something I haven’t tried, I usually set bitcoin as a service on systemd, but this may work too.
Please remember, system administration is not something that you can pick up from an article. It’s the details that get you. Can you set online backups for your wallet file? Can you check the logs if something breaks? Can you fix permission issues? Can you harden the security of your distribution? Can you keep the distribution packages updated to maintain security? All of these things are relevant when you are doing administration work.
If you are unsure about what you’re doing, then ask a professional for help. Otherwise you will be frustrated with all the details.
Best of luck
with regards