Just download it, burn it to a storage device, and connect the storage device to the RPi 5
It will boot up and autostart a script that asks for your personal information. Such as name, username, host name, time zone, desired Desktop Enviroment, etc. When finished it will reboot and you are ready to go.
If you want to use btrfs instead of ext4, this Topic explains how to make your own image with btrfs.