Authorized .Net payment gateway not working

[villadavid]

Hello sir, I have implemented authorized.net payment gateway in my project. When i am running my project, It is saying  -

Warning: require(vendor/autoload.php): failed to open stream: No such file or directory in C:\xampp\htdocs\sample-code-php-master\PaymentTransactions\charge-credit-card.php on line 2

Fatal error: require(): Failed opening required 'vendor/autoload.php' (include_path='.;\xampp\php\PEAR') in C:\xampp\htdocs\sample-code-php-master\PaymentTransactions\charge-credit-card.php on line 2

I have already intalled the composer, but It's not helping me to solve the error .
So how can Solve this problem ?

[Lishmalinyjames]

Authorize.net is UP and reachable by us. The above graph displays service status activity for Authorize.net over the last 10 automatic checks. The blue bar displays the response time, which is better when smaller.