Getting errors using the Cloudflare PHP SDK library

I am using the PHP Cloudflare API to cachePurge certain URLs using the API Token rather the API key and email authentication. I am able to authenticate using the email and API key but not with solely the API token. I am receiving a 403 forbidden response but have checked my credentials and they work with CURL commands in the terminal. Is this an issue that others are experiencing?

So my code is as per the documenation -
$key = new \Cloudflare\API\Auth\APIToken($apiToken); $adapter = new Cloudflare\API\Adapter\Guzzle($key); $zones = new \Cloudflare\API\Endpoints\Zones($adapter); $zones->listZones();
This returns the 403 error but works when I use the APIKey class with $email and $apiKey it works fine.

Does anybody know what the error is or confirm if they have also had problems with authenticating using the API Token class?