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