Friends... my new Raspberry Pi makes me crazy!!!

I would like to install Docker on the RPi5 (8 GB). I am following this guide: https://docs.docker.com/...

However, at step 2:

sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

I always get the error:

E: Package 'docker-ce' has no installation candidate
E: Package 'docker-ce-cli' has no installation candidate
E: Unable to locate package containerd.io
E: Couldn't find any package by glob 'containerd.io'
E: Couldn't find any package by regex 'containerd.io'
E: Unable to locate package docker-buildx-plugin
E: Unable to locate package docker-compose-plugin

Then I found out that at step 1:

sudo apt-get update
sudo apt-get install ca-certificates curl
sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu \
  $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update

I receive the error:

Hit:1 http://deb.debian.org/debian bookworm InRelease
Hit:2 http://deb.debian.org/debian-security bookworm-security InRelease
Hit:3 http://deb.debian.org/debian bookworm-updates InRelease
Hit:4 http://archive.raspberrypi.com/debian bookworm InRelease
Ign:5 https://download.docker.com/linux/ubuntu bookworm InRelease
Err:6 https://download.docker.com/linux/ubuntu bookworm Release
  404  Not Found [IP: 18.165.183.12 443]

What I am doing wrong? :-( What am I missing? Why can't this IP be found?

Many thanks! :-)