20.04 Synaptics package manager not supported [duplicate]

Installing from https://launchpad.net/ubuntu/focal/amd64/synaptic/0.84.6ubuntu5  should work, doesn't Nothing else does.

Failed to install  - file not supported

$ cat /etc/os-release
NAME="Ubuntu"
VERSION="20.04.2 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.2 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal

ubuntu@ubuntu:~$ dpkg --print-architecture
amd64

Use sudo apt-get install synaptic