==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release):  1.4.2
- Deployed with iRedMail Easy or the downloadable installer? downloaded installer
- Linux/BSD distribution name and version: Ubuntu 20.04 LTS
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  MariaDB
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? Not yet ...
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Early in the packages download I saw this:
Err:19 https://packages.inverse.ca/SOGo/nightly/5/ubuntu focal/focal amd64 sogo amd64 5.2.0.20211001-1
  404  Not Found [IP: 184.30.31.114 443]
Err:20 https://packages.inverse.ca/SOGo/nightly/5/ubuntu focal/focal amd64 sogo-activesync amd64 5.2.0.20211001-1
  404  Not Found [IP: 184.30.31.114 443]

And it eventually failed with this:

E: Failed to fetch https://packages.inverse.ca/SOGo/nightl … _amd64.deb  404  Not Found [IP: 184.30.31.114 443]
E: Failed to fetch https://packages.inverse.ca/SOGo/nightl … _amd64.deb  404  Not Found [IP: 184.30.31.114 443]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
<< ERROR >> Installation failed, please check the terminal output.
<< ERROR >> If you're not sure what the problem is, try to get help in iRedMail
<< ERROR >> forum: https://forum.iredmail.org/

Just punt?