BTCPay Server intergration using Greenfield API / php - php

Question

So I am trying to integrate btcpayserver into my site. I am fairly new to php so bare with me but I have everything working until after the invoice is created. Whenever user clicks to pay with bitcoin, it successfully creates new invoice but doesn't redirect to the checkout link afterwards.
I should mention i am using the following to help with integration process https://github.com/btcpayserver/btcpayserver-greenfield-php
Here is my create_invoice.php
session_start();
// Include autoload file.
require __DIR__ . '/../vendor/autoload.php';
// Import Invoice client class.
use BTCPayServer\Client\Invoice;
use BTCPayServer\Client\InvoiceCheckoutOptions;
use BTCPayServer\Util\PreciseNumber;
// Fill in with your BTCPay Server data.
$apiKey = 'aaaaaaaaaa';
$host = 'https://aa.demo.btcpayserver.org/';
$storeId = 'aaaaaa';
$amount = $_POST['amount'];
$currency = 'USD';
$orderId = $_SESSION['name']."#" . mt_rand(0, 1000);
$buyerEmail = $_SESSION['name'];
try {
$client = new Invoice($host, $apiKey);
var_dump(
$client->createInvoice(
$storeId,
$currency,
PreciseNumber::parseString($amount),
$orderId,
$buyerEmail
)
);
} catch (\Throwable $e) {
echo "Error: " . $e->getMessage();
}
Whenever the form is submitted the following is shown (i replaced the sensitive information)
object(BTCPayServer\Result\Invoice)#6 (1)
{
["data":"BTCPayServer\Result\AbstractResult":private] => array(16)
{
["id"]=> string(22) "aaaaaaaaaaa"
["storeId"]=> string(44) "ssssssssssssssssssssssssssss"
["amount"]=> string(4) "18.0"
["checkoutLink"]=> string(62) "https://demo.aa.btcpayserver.org/i/aaaaaaaaaaaaaa"
["status"]=> string(3) "New"
["additionalStatus"]=> string(4) "None"
["monitoringExpiration"]=> int(1669087659)
["expirationTime"]=> int(1669080459)
["createdTime"]=> int(1669078659)
["availableStatusesForManualMarking"]=> array(2)
{
[0]=> string(7) "Settled"
[1]=> string(7) "Invalid"
}
["archived"]=> bool(false)
["type"]=> string(8) "Standard"
["currency"]=> string(3) "USD"
["metadata"]=> array(1)
{
["orderId"]=> string(4) "#501"
}
["checkout"]=> array(10) {
["speedPolicy"]=> string(9) "HighSpeed"
["paymentMethods"]=> array(1)
{
[0]=> string(3) "BTC"
}
["defaultPaymentMethod"]=> NULL
["expirationMinutes"]=> int(30)
["monitoringMinutes"]=> int(120)
["paymentTolerance"]=> float(0)
["requiresRefundEmail"]=> NULL
["defaultLanguage"]=> NULL
}
["receipt"]=> array(3)
{
["enabled"]=> NULL
["showQR"]=> NULL
["showPayments"]=> NULL
}
}
}
Now my issue is I need to redirect to "checkoutLink" after invoice is created.
UPDATE*
Following code displays error "Error: Cannot access offset of type string on string"
if ($response->getStatus() === 200) {
$data1 = $response->getBody();
$link1 = $data1["checkoutLink"];
echo $link1;
} else {
throw $this->getExceptionByStatusCode($method, $url, $response);
}