The new rules for apt-keys need some attentions:
- download an convert the .key file (Release.key) to .gpg
- create a new list file in /etc/apt/source.list.d/
- After all reload source list
wget -O- http://download.sample.com/Release.key |gpg --dearmor | tee /usr/share/keyrings/sample-keyring.gpg
echo "deb [signed-by=/usr/share/keyrings/sample-archive-keyring.gpg] https://download.sample.com/ ./" | sudo tee /etc/apt/sources.list.d/sample.list
apt-get update