The following signatures couldn't be verified because the public key is not available - multi try

I have Ubuntu 20.04 on my WSL and I am facing no pub key error during sudo get-apt update. I went through many questions and everywhere are written almost the same answers like:sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys <KEY> or wget http://download.opensuse.org/repositories/isv:ownCloud:community/xUbuntu_20.04/Release.key but nothing works for me.Full error W: GPG error: https://download.docker.com/linux/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY <KEY> E: The repository 'https://download.docker.com/linux/ubuntu focal InRelease' is not signed.Does anyone have idea what can I do more?