Thank you (everyone) for responses for my frustration / issues. I appreciate it.
I built my machine using Amazon's Lightsail service, and use the Bitnami based server (they present for creation) that has the LAMP stack pre-installed. After feeling that it looks good, and getting hooked on the Bitnami idea, I decided I would try the 'ownCloud' add on.
I pulled down the package and tried the installation on my brand new server, as sudo.
I would say the only config conundrum was the 'base URL' question. It prefills with '127.0.0.1' which is local host only. So should I leave it like that, or give it the server's actual external FQDN? At first I left it at default.
And then I hit all my problems. The biggest being config file access rights by the service as deployed out of the box. While I have the skills to change those by hand, the idea (as I understand it) is that you shouldn't have to.
That all said, I (eventually) tossed all of that and built a new vanilla server based on Ubuntu 16.04, using the generic AWS Lightsail image. Then I added the Bitnami based 'ownCloud' image on top. Nothing more. This answer works 'out of the box'.
Annoyance on this install method is that SMTP isn't installed in the core Ubuntu image. So getting notifications working in the 'ownCloud' install has a lot more manual effort involved.
Overall I think the Bitnami idea is super great to get good software into more hands who would not use it because it is hard for the layman to install and configure on their own. Double plus super kudos for the whole Bitnami idea and project. Everyone who works on this deserves an extra pat on the back, no matter what level of the whole thing that work at.
** for testing, an Amazon Lightsail instance is only $5.00 a month for the smallest version, and can be tossed at any time.