Completing installation, configuration issues - on Ubuntu

EDIT: much of this has been answered here :How to install Freedombox on Ubuntu
SUMMARY: Don’t install Freedombox on Ubuntu unless you know what are (and are not) doing. It just won’t work “out of the box”. Instead, use actual Debian.

ORIGINAL QUESTION

I have an Ubuntu 1804 container running on Proxmox
I’ve followed this instruction.

The packages download and install seemingly ok.

the line

$ sudo /usr/lib/freedombox/setup | tee freedombox-setup.log

doesn’t execute successfully - there is no setup file, or freedombox directory at that location. I can’t find such a file anywhere on the system.

nevertheless, after a reboot I can access plinth using Safari only (Chrome blocks me accessing it due to bad certs( see my post here.

I can set up a user in Freedombox, install apps.
I can’t successfully set up Let’s Encrypt. I get suggested firewall errors (domain name removed):

Failed to obtain certificate for domain <personaldomain>.duckdns.org: 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 <personaldomain>.duckdns.org Using the webroot path /var/www/html for all unmatched domains. Waiting for verification... Cleaning up challenges Failed authorization procedure. <personaldomain>.duckdns.org (http-01): urn:ietf:params:acme:error:connection :: The server could not connect to the client to verify the domain :: Fetching http://<personaldomain>.duckdns.org/.well-known/acme-challenge/fF0RIz3C-2mf5Bpf4_M9KmZuIAUzNo08LIRg9p7BzuU: Timeout during connect (likely firewall problem)

I suspect some configuration of Ubuntu security/firewall is not complete due to the setup command above not working.

Can anyone comment on how I should continue configuration on ubuntu?