I recently set up a client with an AGO Organization and their inspector with an Editor License type within the Organization. When he tries to log into Collector for ArcGIS Classic, he gets an error reading "The specified clientID is invalid" and the app shows the login screen again. The Admin's credentials work fine in Collector and on the desktop, and the inspector's also work on the desktop. The inspector's iPad is running iOS 10.3.4 and his role is Editor. He does not have Collector in his apps bundle, although the Collector info page says "Collector for ArcGIS is available to members of ArcGIS organizations. This includes those with a subscription to ArcGIS Online or an account on ArcGIS Enterprise." Which means my client should have access? Did this switch when ESRI released the Field Worker License type? Does anyone recognize the error?