I can't seem to get the resource proxy working with unfederated (built in security) ArcGIS Server 10.5.1. I used to do this all the time back in the day but can't get it working with the latest stuff. I can't get the resource proxy to return a token to access secured services.
Token obtained: Exception in generating tokenFailed to generate a token for the user.Client ID is required for long expiration tokens.
Any idea what I'm doing wrong?