To retrieve the SDK user status you should use the GetUserStatus() function. 
  ZBDUtilities.Instance.GetUserStatus(callback =>
  {
    if (callback.success)
    {
      Debug.Log("user status success");
      Debug.Log(callback.data.status);

      if (callback.data.status == ZBDConstants.ZBD_LINKED_STATUS)
      {
        Debug.Log("zbd linked");
      }
    }
    else
    {
      Debug.LogError("user status error " + callback.message);
    }
  });
This returns a ZBDUserStatusResponse object which contains a ZBDUserStatus object that has following data: 
public class ZBDUserStatusResponse
{
  public bool success { get; set; }
  public string message { get; set; }
  public ZBDUserStatus data { get; set; }
}

public class ZBDUserStatus
{
  // the user's linked status
  public string status { get; set; }
  // the user's sdk id
  public string rewardsUserId { get; set; }
  // the user's zbd id
  public string zbdUserId { get; set; }
}

​
Status Types

The status parameter can be:
  • unlinked: User has not signed up for rewards, meaning they have not clicked Start Earning
  • linked: User has signed up for rewards, meaning they have clicked Start Earning
  • zbdlinked: User has signed up for rewards, clicked Start Earning, and linked their ZBD account