Google API v4 Sheets setSubject Unauthorized Client

Question

I'm using the Google API v4 in a Laravel project to write to Google Sheets. I am able to create sheets and share them with a particular user, but I wish to use the setSubject() method to impersonate a user so sharing is not necessary.

I have Domain wide Delegation set up but I am receiving this error:

[Google_Service_Exception]
{
  "error": "unauthorized_client",
  "error_description": "Unauthorized client or scope in request."
}