Difficulty installing 28.0.1 for local use

Hardware is Raspberry Pi aarch64
OS is Raspberry Pi OS (Debian bookworm 12)
My intention is to install nextcloud on a headless device to access and sync over the LAN.
I pulled latest.zip and version.php shows:

<?php 
$OC_Version = array(28,0,1,1);
$OC_VersionString = '28.0.1';
$OC_Edition = '';
$OC_Channel = 'stable';
$OC_VersionCanBeUpgradedFrom = array (
  'nextcloud' => 
  array (
    '27.0' => true,
    '27.1' => true,
    '28.0' => true,
  ),
  'owncloud' => 
  array (
    '10.13' => true,
  ),
);
$OC_Build = '2023-12-21T15:34:10+00:00 62d83123d1272d2d042ec294c6d65cd79bbc05ca';
$vendor = 'nextcloud';

I have also created a minimalist config.php file in nextcloud/config/

ls -l nextcloud/config/
total 80
-rw-r--r-- 1 www-data www-data     0 Dec 22 02:29 CAN_INSTALL
-rw-r----- 1 www-data www-data   272 Feb  5 12:59 config.php
-rw-r--r-- 1 www-data www-data 76941 Dec 22 02:29 config.sample.php
<?php
$CONFIG = array (
  'datadirectory' => '/var/www/html/nextcloud/data',
  'dbtype' => 'mysql',
  'dbhost' => 'localhost',
  'dbname' => 'nextcloud',
  'dbuser' => 'xxxxxx',
  'dbpassword' => 'xxxxxx',
  'dbtableprefix' => 'nc_',
);

I have mysql (mariadb) installed on this device.
The entire installation is owned, root and group, by www-data

When I call up the site in the web browser I get a screen asking to create an admin account, but it then chides me that I am trying to use a sqlite database instead of the mysql database that is defined in config.php (yes, sqlite3 is installed on the device).

On other occasions I have been confronted with a 500 screen and got nowhere.

What is going wrong? I chose to come over to nextcloud because of the attitudes over at owncloud; don’t make me regret the decision.