For Ubuntu 20.04 see: https://linuxconfig.org/ubuntu-20-04-server-installation
Remember, no stress, installing a server can be fun! Consider that many people did it before you and there are many guides. It's not rocket science, and you will join a vast group of people dealing with machines!
Our purpose is to simplify all this complexity and give some simple input to be followed. We also stress some key points and essential features/tools. The overall process should work as follows:
An USB pen is needed, you have to download the chosen GNU/Linux and burn it onto the USB key
Stick the key onto a USB port of the server
Start the server choosing the USB key as first running device
Follow the instructions
Have fun :D