I put interview in quotes because they called it an interview. Speaking broadly enough, all interviews are tests, but most are unstructured and not very good at examining the relevant predictor variables. All tests are of course not necessarily interviews, but the part where they had applicants explain their processes in layman's terms might qualify it, at least if you're generous with your definitions.

Of course, it's certainly unclear if not outright incorrect to call it an interview, but that was their choice; possibly they felt that subjecting applicants to a "test" rather than an "interview" projected a less positive image.