Trying to add GPG keys

When I add any software to my Whonix package manager, I get the following error:

W: GPG error: [url] default InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY [letters/numbers of key]

Did you add a repository? Then you messed that up and did it incomplete.

Not a Whonix issue.

Yes. When I follow the guides from the software devs, it works on other distros but not Whonix.

For example Element,

Debian / Ubuntu x86_64 / aarch64
sudo apt install -y wget apt-transport-https

sudo wget -O /usr/share/keyrings/element-io-archive-keyring.gpg

echo “deb [signed-by=/usr/share/keyrings/element-io-archive-keyring.gpg] default main” | sudo tee /etc/apt/sources.list.d/element-io.list

sudo apt update

sudo apt install element-desktop