I applied online, and then found a few employees internally through my connections who also passed on my CV. It still took them 3 months to get back to me indicating interest (which I was surprised they were at that point). I was instructed to do an online personality test at first. Based on the results HR then proceeded to schedule an interview with the manager via an automated process. Interview was fairly relaxed, behavioral/experience based.
What was irritating was the fact that Transferwise preaches the utmost in customer centricity in everything they do, but after my interview didn't have the decency to get back to me with a simple rejection declining my candidacy. I know I won't be using Transferwise anytime soon.