When I step through it features claimed in the git hub text are inaccurate for release 16.3 - the users and user group are NOT created automatically by the pkg install
When they are manually created and given full access to both source and destination mount points the error permission denied to a folder structure not stated in the mount points is returned - what am I to do ? Read the manual. I have and it is utterly obtuse what to do.
The guide you found seems reasonable and I'd expect the pkg installation to create the users/groups it requires. If it doesn't it is odd and should be taken up with the group providing the installation package. The official documentation takes the position that it will not try and keep up with the many various packaging systems out in the wild. So you will not find helpful advice in it on how to perform a package-based installation and configuration. All it covers is a source code compilation installation which is not what you want to do.
If you want to search out someone to help the -general mailing list, Reddit, Slack, Discord, IRC and probably other places are where people willing to help in that way hang out.
Assuming TrueNAS is indeed built on top FreeBSD as described, and you can get whatever its equivalent of "root" is to perform all of the actions shown, PostgreSQL should work, not caring that it is running inside an appliance. But we also don't have anyone running a TrueNAS device in our build farm so it specifically isn't getting tested (FreeBSD is I believe) on a daily basis. Though even at that it is the source builds we test, not packages.
