Add the repository.

echo 'deb http://download.proxmox.com/debian/pdm bookworm pdm-test' >/etc/apt/sources.list.d/pdm-test.list

Download the Proxmox release key.

wget https://enterprise.proxmox.com/debian/proxmox-release-bookworm.gpg -O /etc/apt/trusted.gpg.d/proxmox-release-bookworm.gpg

Install the package.

apt update
apt install -y proxmox-datacenter-manager proxmox-datacenter-manager-ui

Enter Y if you want to be part of the pdm-test repository for the latest features

After installation the GUI will be available on port 8443.