第三方Google Analytics sdk问题

I have code which works above the php 5

its actually GA Library, here is its github project.

I have cloned the project theiconic/php-ga-measurement-protocol

Since I am new to PHP, I have no idea where to put this code, Please help me here this project should be installed via composer via code

{
    "require": {
        "theiconic/php-ga-measurement-protocol": "^2.0"
    }
}

After this step I need to create a file something.php and I need to put the code below, I am having problem on locating autoload.php on my server, Please look at the code below to understand what i am saying.

<?php
        //grab the data that Calendly sent in the webhook and store it in a variable called $objCalendlySubmission...
        $objCalendlySubmission = json_decode(file_get_contents('php://input'));

        //We've passed the Google client_id in Calendly's placeholder for utm_term. Feel free to pass it differently, this is just an example
        if(property_exists($objCalendlySubmission->payload->tracking, 'utm_term') && !empty($objCalendlySubmission->payload->tracking->utm_term)) {
            $strPageViewed = 'calendly_conversion.html'; // We use different page names depending on what type of event was scheduled via Calendly
            sendGoogleAnalyticsPageView($objCalendlySubmission->payload->tracking->utm_term, $strPageViewed);
        }

        function sendGoogleAnalyticsPageView($strGAClientId, $strURL) {
            require_once '/path_to_composer/composer/vendor/autoload.php'; //loads the PHP library for the "Google Analytics Measurement Protocol” **I dont know where is it located exactly on my xampp server, Please guide me here**
            $analytics = new TheIconic\Tracking\GoogleAnalytics\Analytics(true); //you may have to adjust this path based on your setup **please help me here**

            $analytics
                ->setProtocolVersion('1')
                ->setTrackingId('YOUR-GA-UA-ID-GOES-HERE')
                ->setClientId($strGAClientId)
                ->setDocumentLocationUrl($strURL);

            $analytics->sendPageview(); 
        }
        ?>

In the above code towards middle line

require_once '/path_to_composer/composer/vendor/autoload.php'; //loads the PHP library for the "Google Analytics Measurement Protocol” 

I dont know where is it located exactly on my xampp server, Please guide me here

$analytics = new TheIconic\Tracking\GoogleAnalytics\Analytics(true); //you may have to adjust this path based on your setup 

Here is the image of Project folder

Project structure Part 2