Ok, I wasn't aware of iredadmin running as a service. Thought it was just a webapp running under nginx. Looks like it tossed an error.

● iredadmin.service - iRedAdmin daemon service
   Loaded: loaded (/lib/systemd/system/iredadmin.service; enabled; vendor preset: enabled)
   Active: active (running) since Thu 2020-07-30 17:55:00 EDT; 16h ago
  Process: 440 ExecStartPre=/bin/mkdir -p /var/run/iredadmin (code=exited, status=0/SUCCESS)
  Process: 447 ExecStartPre=/bin/chown iredadmin:iredadmin /var/run/iredadmin (code=exited, status=0/SUCCESS)
  Process: 460 ExecStartPre=/bin/chmod 0755 /var/run/iredadmin (code=exited, status=0/SUCCESS)
Main PID: 463 (uwsgi)
    Tasks: 6 (limit: 2347)
   Memory: 5.7M
   CGroup: /system.slice/iredadmin.service
           ├─463 /usr/bin/uwsgi --ini /opt/www/iredadmin/rc_scripts/uwsgi/debian.ini --pidfile /var/run/iredadmin/iredadmin.pid
           ├─498 /usr/bin/uwsgi --ini /opt/www/iredadmin/rc_scripts/uwsgi/debian.ini --pidfile /var/run/iredadmin/iredadmin.pid
           ├─499 /usr/bin/uwsgi --ini /opt/www/iredadmin/rc_scripts/uwsgi/debian.ini --pidfile /var/run/iredadmin/iredadmin.pid
           ├─500 /usr/bin/uwsgi --ini /opt/www/iredadmin/rc_scripts/uwsgi/debian.ini --pidfile /var/run/iredadmin/iredadmin.pid
           ├─501 /usr/bin/uwsgi --ini /opt/www/iredadmin/rc_scripts/uwsgi/debian.ini --pidfile /var/run/iredadmin/iredadmin.pid
           └─502 /usr/bin/uwsgi --ini /opt/www/iredadmin/rc_scripts/uwsgi/debian.ini --pidfile /var/run/iredadmin/iredadmin.pid

Jul 30 18:32:23 mailserv uwsgi[463]:   File "/opt/www/iRedAdmin-1.0/libs/iredbase.py", line 7, in <module>
Jul 30 18:32:23 mailserv uwsgi[463]:
Jul 30 18:32:23 mailserv uwsgi[463]: import web
Jul 30 18:32:23 mailserv uwsgi[463]: ImportError
Jul 30 18:32:23 mailserv uwsgi[463]: :
Jul 30 18:32:23 mailserv uwsgi[463]: No module named web
Jul 30 18:32:23 mailserv uwsgi[463]:
Jul 30 18:32:23 mailserv uwsgi[463]: unable to load app 0 (mountpoint='192.168.5.6|/iredadmin') (callable not found or import error)
Jul 30 18:32:23 mailserv uwsgi[463]: --- no python application found, check your startup logs for errors ---
Jul 30 18:32:23 mailserv uwsgi[463]: 192.168.5.6 [pid: 501|app: -1|req: -1/3] 192.168.5.101 () {62 vars in 1028 bytes} [Thu Jul 30 18:32:23 2020] GET /iredadmin/ => generated 21 bytes in 13 msecs (HTTP/1.1

That appears to have fixed it. Any ideas as to why that wouldn't have been done in the install script? Thanks for the assist.

1.3.1 MARIADB edition.
Installed via downloadable installer.
FreeBSD 12.1-RELEASE-p7 fresh install
Nginx

I have just completed a fresh install on a clean FreeBSD 12.1-RELEASE-p7 server. On attempting to access the iredadmin page I get the message:
Internal Sever Error.

No errors were seen during the install I do have a /usr/local/www/iredadmin -> /usr/local/www/iRedAdmin-1.0

freebsd is currently broken as mentioned in release notes. I’m afraid that you have to run iRedMail-1.3.1 on FreeBSD without iRedAdmin(-Pro), or wait for some more days.

RE: any error on console during installation?

Then install via downloadable installer error with uswgi setup. No errors then GitHub but in logs uswgi could not connect to port.
I think problem with uwsgi