• you don't run DokuWiki as a systemd service. DokuWiki is a PHP application and PHP applications don't run as service. PHP applications rely on the webserver to launch various PHP scripts on demand; for each HTTP request. In your case, you have to set up a php-fpm service -- whose job is to actually interpret the PHP scripts -- and configure nginx to pass requests to that php-fpm service. To install php-fpm, refer to your particular distro documentation, but this is usually as simple as installing the php-fpm package. Once done, see https://www.dokuwiki.org/install:nginx
to setup nginx. The example is given for dokuwiki at the root of a website. So, you have to change "location /" to "location /wiki", "location /lib" to "location /wiki/lib", "rewrite ^/_media" to "rewrite ^/wiki/_media" and so on...
• Once done, run the installer. (it will be htt
ps://order.life/wiki/install.php). see https://www.dokuwiki.org/installer
, this will create the required minimum settings. Among other things, it will create conf/local.php
• Never edit conf/dokuwiki.php, but override default settings in conf/local.php . See https://www.dokuwiki.org/config
• Usually, there is nothing to configure in DokuWiki to tell it it is located at /something. DW autodetects its own URL. If it does not work properly (images not shown for example), then set basedir in conf/local.php. It might help. See https://www.dokuwiki.org/config:basedir
You might also want to read the whole install documentation. https://www.dokuwiki.org/install