Getting error while install jitsi in ubuntu

Err:7 https://download.jitsi.org stable/ Release
Certificate verification failed: The certificate is NOT trusted. The certificate chain uses expired certificate. Could not handshake: Error in the certificate verification. [IP: 130.79.200.22 443]

did you add the key?

wget -qO - https://download.jitsi.org/jitsi-key.gpg.key | sudo apt-key add -

do an apt-get update & apt-get install apt-transport-https