The automatic plugin installer should work for most people. Manual installation is easy and takes fewer than five minutes.
- Create a wplistcal-json directory in your plugins directory. Typically that's wp-content/plugins/wplistcal-json/.
- Into this new directory upload the plugin files (wplistcal-json.php, etc.)
- Activate the plugin through the 'Plugins' menu in WordPress.
- Activate the 'WPListCal' controller through the 'JSON API' options page.