What is the cause of the error during the BigBlueButton 2.3 installation script and how to fix it?

Question

linux

I'm trying to install BigBlueButton on an Ubuntu 18.04.5 LTS server using this manual . After the preparatory procedures, the installation of BBB is performed by a script , during which an error occurs. Here is the console log .
As far as I understood from the text of the log, the reason for the installation failure is that installation from unsigned repositories is prohibited.
Am I right? And if so, how can Ubuntu allow installation of packages from unsigned repositories? Is there some global setting?

Answer 1

gnupg, gnupg2 and gnupg1 do not seem to be installed, but one of them is required for this operation

Install one thing and run the installation, it should work, because judging by the appeal to

https://ubuntu.bigbluebutton.org/repo/bigbluebutton.asc

the key is trying to add, but due to the lack of the necessary software, it cannot.