When installing DokuWiki as a desktop wiki on a Mac (and possible also other OS) only PHP is needed. You can use the build-in PHP webserver. See PHP build-in webserver for more information.

Your Mac comes with PHP included. As I am on OS X El Capitan my included PHP version is 5.5.38. The newest OS X High Sierra comes with PHP 7.1.

Download DokuWiki and extract the files in a directory of your choosing. In this directory (containing the doku.php and index.php file) open a terminal and type in the following:

php -S localhost:8000

This will start the PHP webserver. Going to http://localhost:8000 will show you your DokuWiki start page. Run the install.php if it is a new installation. A terminal window will stay open while you are running the server. If you do not want that read further.

On a mac you can use Automator to create an APP file. Choose to create an application and choose to run a terminal command. Use the command mentioned above. When you safe Automator askes you where to store the .app file. You can safe it in you Applications folder.

When you start it the server will be started without a terminal window. To close the webserver you need to kill it in the ActivityMonitor.

I am running a vanilla DokuWiki without any additional plugins with this install method for a couple of days now without any trouble. As mentioned on the PHP build-in webserver page this install is not usable for any production environment. But seems to me it is ok for a local desktop wiki.