How can I improve my chances of being hired at Avant?

Know something about the company- both Avant and Amount! Know their main two products (unsecured loans & credit cards) as well as their fee/price ranges, know the credit space in which they play ("near prime"), understand the basics of financial modeling (cost to acquire customer, expected cash flows during the customer's lifetime), know something about the founder, Al Goldstein (the man has a hell of a story). Ask good questions. What's the culture like? How do the (many) different teams work together? What differentiates Avant from competitors? What are biggest challenges to growth? What media channels do they use to acquire customers? What sort of data do they use, where do they get it, and how do they store it? What kind of predictive underwriting models do they use? Have some sort of technical skills: SQL and Python are ubiquitous here. At the very least, know how to make a dashboard.

Be well prepared with a personalized resume` and cover letter, research the company in-depth, and really tailor your responses to common interview questions for why you are interested in the position and specifically Avant. Make sure you understand the culture of the company and the team you're applying for and show and how you'd fit, as well as what value you would bring if hired.