FINALLY got NextCloud 16.0.3 installed on my Dell server! Right now it's only local and unencrypted. But I can play with it a little for now!

Most of my install problems were due to me assuming I had to do more than I needed to. For example in older versions you had to manually set up the nextcloud's databases in MySQL. I also had to give MySQL a root password or at least I assumed I did. So I could specify it in the NextCloud setup. Because as installed, MySQL is just administered 'sudo mysql -u root'.