DEVELOPER_TOKEN_NOT_APPROVED by Google Ads API for PHP

I want to use the Google Ads API to access Google Ads reports. As a preliminary step, we want to use the GoogleCustomerServiceClient to retrieve customer information.

$MMC_ID = <My MMC 10 digits number>; $credentialsIniPath = app_path('resources/credentials/google/google_ads_php.ini'); $oAuth2Credential = (new OAuth2TokenBuilder())     ->fromFile($credentialsIniPath)     ->build(); $googleAdsClient = (new GoogleAdsClientBuilder())     ->fromFile($credentialsIniPath)     ->withOAuth2Credential($oAuth2Credential)     ->build(); $customerServiceClient = $googleAdsClient->getCustomerServiceClient(); try {     $customer = $customerServiceClient->getCustomer(ResourceNames::forCustomer($MMC_ID)); } catch(GoogleAdsException $e) {     $this->error($e->getMessage()); } 

But it returns an error

Fault ------- Status code: 7 Details: The caller does not have permission Failure: {"errors":[{"errorCode":{"authorizationError":"DEVELOPER_TOKEN_NOT_APPROVED"},"message":"The developer token is not approved. Non-approved developer tokens can only be used with test accounts."}]} 

The account Oauth2 login that created MMC, MMC is a test account. In google_ads_php.ini, clientId, clientSecret, refreshToken, and developerToken are already filled in. The refreshToken has just been generated.

What should I check for in this one?

Thanks.