Step 1 - coding challenge: you're given 1 hour to solve a leetcode easy problem. They put a focus on coding style over performance.
Step 2 - phone interview: there are three parts of this phone screen: (1) a casual chat for ~10 minutes (2) leetcode-style coding problem over Google Docs, where you only have to write pesudo code (3) system design problem
Step 3 - onsite: Asana's onsite interview is very different from other companies. The care a lot about if they can work with you on a daily basis over if you can come up with the optimal solution using fancy data structures. I had 3 interviews: (1) system design for 40 minutes + 20-minute coding question (2) 50-minute solo coding session (where you actually code out the solution to a pretty interesting problem on your own laptop) (3) you talk through your code with an interviewer, with the focus on your understanding of the tradeoffs of your design decisions
In short, they really care about you being a great software engineer, rather than a computer scientist.