The first day you will come into the office to take and aptitude test. If you past the test you will be granted an in person interview for a future date.
The day of the in person interview I was asked to show off portfolio pieces that highlight data visualization, iconography, and dashboards.
Additionally they will judge you to see how you would fit in the office culture. If you are a very politically correct individual who takes themselves to seriously you probably won't make it to far. I would argue that fitting into the office culture matters more than your portfolio.
After the in person interview you will be introduced to the UI/UX team and other people that you will interact with on a daily basis.
It took about a week to hear a response after the interview, depending on how bad they need a designer.