sendgrid unauthorized. Wrong credentials - php - php

Question

I'm trying to implement sendgrid to my project and I have a basic function running the following:
require '../vendor/autoload.php'; // If you're using Composer (recommended)
// Comment out the above line if not using Composer
// require("<PATH TO>/sendgrid-php.php");
// If not using Composer, uncomment the above line and
// download sendgrid-php.zip from the latest release here,
// replacing <PATH TO> with the path to the sendgrid-php.php file,
// which is included in the download:
// https://github.com/sendgrid/sendgrid-php/releases
$email = new \SendGrid\Mail\Mail();
$email->setFrom("test#example.com", "Example User");
$email->setSubject("Sending with SendGrid is Fun");
$email->addTo("tiernoyt#gmail.com", "Example User");
$email->addContent("text/plain", "and easy to do anywhere, even with PHP");
$email->addContent(
"text/html", "<strong>and easy to do anywhere, even with PHP</strong>"
);
$sendgrid = new \SendGrid($_ENV['SENDGRID_API_KEY']);
try {
$response = $sendgrid->send($email);
print $response->statusCode() . "\n";
print_r($response->headers());
print $response->body() . "\n";
} catch (Exception $e) {
echo 'Caught exception: '. $e->getMessage() ."\n";
}
}
I get the error "permission denied: wrong credentials". I have the environmental variable set, I tried to put the value of the key with quotes and no quotes. It is also in my sendgrid.env file (which is gitignored) as the following line
export SENDGRID_API_KEY='XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
If I change the code to $apiKey = 'xxxxxx'; $sendgrid = new \SendGrid($api); then it works. So it is obviously an error fetching the variable but I'm not sure as to why