You can install the Arlo plugin for WordPress via the WordPress automatic plugin installation, just search for "Arlo event"

You can download the plugin from the WordPress Plugin Directory and you can install it manually

The minimum required PHP version for the plugin is 5.5 and from version 3.2 it's also compatible with PHP 7

During the installation, the plugin creates pages and you have to publish those pages to reach the plugin within your WordPress instance. When it's done, go to the Settings menu and go to the Arlo settings page. Under the general section, fill in your platform name and save the settings. It will run an import, which can take a while, but when it's finished, the plugin is ready to use.

If you want to modify the settings, or modify the existing templates, you can do this on the WordPress Arlo settings page.

Note that the plugin is manipulating database tables, so you will need the permissions to be set properly to allow CREATE, DROP and ALTER at least on all wp_arlo_* tables, especially during the plugin upgrade process.