Big Blue Button installation error: "Challenge failed for domain", thereafter "500 Internal Server Error -- nginx"

**Context:** - I wanted to install Big Blue Button on a Ubuntu virtual machine via SSH; - I followed correctly the official tutorial up to the "Install" section ; - I entered the following command on the terminal: wget -qO- https://raw.githubusercontent.com/bigbluebutton/bbb-install/v2.7.x-release/bbb-install.sh | bash -s -- -w -v focal-270 -s -e -g -k using real data on "here the domain name" and "here the email"; - I got **the instalation error** detailed below; - Accessing the real "here the domain name" by HTTP gives me "500 Internal Server Error -- nginx"; - It is not accessible by HTTPS: "ERR_CONNECTION_REFUSED". **The installation error** in its full glory: A instalar certbot (0.40.0-1ubuntu0.1) ... Created symlink /etc/systemd/system/timers.target.wants/certbot.timer → /lib/systemd/system/certbot.timer. A processar 'triggers' para man-db (2.9.1-1) ... Saving debug log to /var/log/letsencrypt/letsencrypt.log Plugins selected: Authenticator webroot, Installer None Obtaining a new certificate Performing the following challenges: http-01 challenge for Using the webroot path /var/www/bigbluebutton-default/assets for all unmatched domains. Waiting for verification... Challenge failed for domain http-01 challenge for Cleaning up challenges Some challenges have failed. IMPORTANT NOTES: - The following errors were reported by the server: Domain: Type: caa Detail: CAA record for prevents issuance - Your account credentials have been saved in your Certbot configuration directory at /etc/letsencrypt. You should make a secure backup of this folder now. This configuration directory will also contain certificates and private keys obtained by Certbot so making regular backups of this folder is ideal. bbb-install: Let's Encrypt SSL request for did not succeed - exiting **The Let's Encrypt log** in its full glory: - https://sprunge.us/pQGlat **Questions:** 1. since the problem appears to have started with the SSL certificate during installation, disabling/removing it could solve the "500 Internal Server Error"? 2. if yes, how to do it without uninstalling and reinstalling Big Blue Button? (I suppose uninstalling and reinstalling would be more traumatic due to leaving residues behind to create brand new errors) 3. if no, how to troubleshoot the "500 Internal Server Error", finding its cause and solution?