Foreman-proxy installation fails

Problem:
Following these insctructions: Installing an External Smart Proxy Server on Debian/Ubuntu To install a Smart Proxy on an ISC DHCP server and the install fails.

Expected outcome:
Wasn’t expecting errors

Foreman and Proxy versions:
3.4.0 for both

Foreman and Proxy plugin versions:
n/a

Distribution and version:
Foreman 3.4.0 on CentOS Stream 8
Proxy 3.4.0 on Ubuntu 20.04

Other relevant data:
Executed command:

foreman-installer \
  --no-enable-foreman \
  --no-enable-foreman-cli \
  --enable-puppet \
  --puppet-server-ca=false \
  --puppet-server-foreman-url=https://fm.domain.com \
  --enable-foreman-proxy \
  --foreman-proxy-puppetca=false \
  --foreman-proxy-tftp=false \
  --foreman-proxy-foreman-base-url=https://fm.domain.com \
  --foreman-proxy-trusted-hosts=fm.domain.com \
  --foreman-proxy-oauth-consumer-key=****** \
  --foreman-proxy-oauth-consumer-secret=******

Tail of /var/log/foreman-installer/foreman.log:

2022-11-07 16:30:21 [DEBUG ] [configure] importing '/usr/share/foreman-installer/modules/systemd/manifests/install.pp' in environment production
2022-11-07 16:30:21 [DEBUG ] [configure] Automatically imported systemd::install from systemd/install into production
2022-11-07 16:30:21 [DEBUG ] [configure] importing '/usr/share/foreman-installer/modules/systemd/manifests/journald.pp' in environment production
2022-11-07 16:30:21 [DEBUG ] [configure] Automatically imported systemd::journald from systemd/journald into production
2022-11-07 16:30:21 [DEBUG ] [configure] importing '/usr/share/foreman-installer/modules/systemd/manifests/daemon_reload.pp' in environment production
2022-11-07 16:30:21 [DEBUG ] [configure] Automatically imported systemd::daemon_reload from systemd/daemon_reload into production
2022-11-07 16:30:21 [DEBUG ] [configure] Resource systemd::daemon_reload[puppetserver.service] was not determined to be defined
2022-11-07 16:30:21 [DEBUG ] [configure] Create new resource systemd::daemon_reload[puppetserver.service] with params {}
2022-11-07 16:30:21 [DEBUG ] [configure] importing '/usr/share/foreman-installer/modules/foreman/manifests/cli/params.pp' in environment production
2022-11-07 16:30:21 [DEBUG ] [configure] Automatically imported foreman::cli::params from foreman/cli/params into production
2022-11-07 16:30:21 [DEBUG ] [configure] Unknown variable: 'foreman::cli::params::hammer_plugin_prefix'. (file: /usr/share/foreman-installer/modules/foreman/manifests/cli/plugin.pp, line: 12, column: 24)
2022-11-07 16:30:21 [DEBUG ] [configure] Unknown variable: 'foreman::plugin_version'. (file: /usr/share/foreman-installer/modules/foreman/manifests/plugin.pp, line: 24, column: 24)
2022-11-07 16:30:21 [DEBUG ] [configure] importing '/usr/share/foreman-installer/modules/foreman/manifests/params.pp' in environment production
2022-11-07 16:30:21 [DEBUG ] [configure] Automatically imported foreman::params from foreman/params into production
2022-11-07 16:30:21 [DEBUG ] [configure] Unknown variable: 'foreman::params::plugin_prefix'. (file: /usr/share/foreman-installer/modules/foreman/manifests/plugin.pp, line: 25, column: 27)
2022-11-07 16:30:21 [DEBUG ] [configure] Unknown variable: 'foreman::plugin_config_dir'. (file: /usr/share/foreman-installer/modules/foreman/manifests/plugin.pp, line: 26, column: 42)
2022-11-07 16:30:21 [DEBUG ] [configure] Unknown variable: 'foreman::group'. (file: /usr/share/foreman-installer/modules/foreman/manifests/plugin.pp, line: 28, column: 34)
2022-11-07 16:30:21 [ERROR ] [configure] Evaluation Error: Error while evaluating a Resource Statement, Foreman::Plugin[puppet]:
2022-11-07 16:30:21 [ERROR ] [configure] parameter 'version' expects a String value, got Undef
2022-11-07 16:30:21 [ERROR ] [configure] parameter 'config_file_group' expects a String value, got Undef (file: /usr/share/foreman-installer/modules/foreman/manifests/plugin/puppet.pp, line: 6) on node ds00.ixbru.ipnexia.com
2022-11-07 16:30:21 [DEBUG ] [configure] Found in cache :production (ttl = 0 sec)
2022-11-07 16:30:21 [NOTICE] [configure] System configuration has finished.
2022-11-07 16:30:21 [INFO  ] [post] Executing hooks in group post
2022-11-07 16:30:21 [DEBUG ] [post] Hook /usr/share/foreman-installer/hooks/post/30-upgrade.rb returned nil
2022-11-07 16:30:21 [DEBUG ] [post] Hook /usr/share/foreman-installer/hooks/post/34-pulpcore_directory_layout.rb returned nil
2022-11-07 16:30:21 [DEBUG ] [post] Hook /usr/share/foreman-installer/hooks/post/99-post_install_message.rb returned nil
2022-11-07 16:30:21 [DEBUG ] [post] Hook /usr/share/foreman-installer/hooks/post/99-version_locking.rb returned nil
2022-11-07 16:30:21 [INFO  ] [post] All hooks in group post finished
2022-11-07 16:30:21 [DEBUG ] [pre_exit] Hook /usr/share/foreman-installer/hooks/pre_exit/20-certs_regenerate.rb returned nil
2022-11-07 16:30:21 [DEBUG ] [root] Exit with status code: 1 (signal was 1)
2022-11-07 16:30:21 [DEBUG ] [root] Cleaning /tmp/kafo_installation20221107-735635-1v1zmzg
2022-11-07 16:30:21 [DEBUG ] [root] Cleaning /tmp/kafo_installation20221107-735635-10g6nn7
2022-11-07 16:30:21 [DEBUG ] [root] Cleaning /tmp/default_values.yaml
2022-11-07 16:30:21 [DEBUG ] [root] Installer finished in 5.056256477 seconds