The building had no formal entrance and there was no way of entering the building so I could not inform the interviewer of my arrival. I had not been given any contact details. Contacted HR to advise my situation but was no help. Was then let in by an employee and was made to wait in the kitchen area. The interviewer arrived with a colleague who both introduced themselves. He explained that this was an informal interview and took no ID or asked for any documents even upon my insistence. They basically were interviewing me without seeing any documents or verifying who I was. Explained my background, academic skills and hobbies.