AlgoliaBehavior.php

<?php
namespace App\Model\Behavior;

use Cake\ORM\Behavior;

class AlgoliaBehavior extends Behavior
{
    protected $_defaultConfig = [
        'index' => '',
        // Other Algolia API key configuration
    ];

    public function afterSave($event, $entity)
    {
        // use client from tutorial link assuming that the index is set.
        $client = $this->getAlgoliaClient();
        // push to algolia
        $client->saveObject($entity->toArray());
    }

    public function afterDelete($event, $entity)
    {
        // use client from tutorial link assuming that the index is set.
        $client = $this->getAlgoliaClient();

        // Find the model's primary key, assuming a non-composite pk
        $schema = $this->getTable()->getPrimaryKey();

        // Remove from algolia
        $client->deleteObject($entity->get($primaryKey));
    }
}

It works great ;)