Install on clean Focal fails with repo signature problems.

[HeneryH]

root@kaltura:~# apt update

Hit:1 http://security.ubuntu.com/ubuntu focal-security InRelease
Get:2 http://installrepo.kaltura.org/repo/aptn/focal propus InRelease [1,426 B]
Hit:3 http://archive.ubuntu.com/ubuntu focal InRelease
Err:2 http://installrepo.kaltura.org/repo/aptn/focal propus InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY DE7AA37623C65ECB
Hit:4 http://archive.ubuntu.com/ubuntu focal-updates InRelease
Hit:5 http://archive.ubuntu.com/ubuntu focal-backports InRelease
Reading package lists... Done
W: GPG error: http://installrepo.kaltura.org/repo/aptn/focal propus InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY DE7AA37623C65ECB
E: The repository 'http://installrepo.kaltura.org/repo/aptn/focal propus InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

[s0faking]

you can run

apt-key adv --keyserver keyserver.ubuntu.com --recv-keys DE7AA37623C65ECB