使用Google API将外部用户添加到G Suite组

Problem:

Corporate Google Drive is not yet able to open team drives to the entire Internet.

I don’t want to move a folder to a personal disk - it’s convenient to work with a team on a team drive.

How I want to solve the problem:

1. There is a form at https://leadstartup.ru/go
2. After filling out this form, the user's email must be added via the API to the G Suite group in order to access the General Drive on Google Drive.

What is done:

1. Written class, which in theory should correctly work out

use Google_Client;
use Google_Service_Directory;
use Google_Service_Directory_Member;

class GoogleClient
{

    /**
     * Returns an authorized API client.
     * @return Google_Client the authorized client object
     */
    private function getClient()
    {
        $client = new Google_Client();
        $client->useApplicationDefaultCredentials();
        $client->setApplicationName("LeadStartup");
        $client->setScopes([
            Google_Service_Directory::ADMIN_DIRECTORY_GROUP,
            Google_Service_Directory::ADMIN_DIRECTORY_GROUP_MEMBER,
            Google_Service_Directory::ADMIN_DIRECTORY_USER
        ]);

        $client->setSubject('a.kolomensky@leadstartup.ru');

        return $client;
    }

    public function addEmailToPublicGroup()
    {
        $member = new Google_Service_Directory_Member();
        $member->setEmail('m.ryazhenka@leadstartup.ru');
        $member->setRole('MEMBER');

        $directory = new Google_Service_Directory($this->getClient());
        $directory->members->insert('friends@leadstartup.ru', $member);
    }
}

2. A service account is registered

Domain-wide delegation enabled.

3. json-file is correct and set to env

putenv('GOOGLE_APPLICATION_CREDENTIALS=' . __DIR__ . '/private/LeadStartup-8c8edffdb357.json');

4. Scopes was added to G Suite

As a result, I get 401 error unauthorized_client Client is unauthorized to retrieve access tokens using this method, or client not authorized for any of the scopes requested.

Please, help me with this issue. What I'm missing?