They don't have a standard interviewing process. I found out that they hire authors on their website and I decided to apply and see how will it all go. I wrote an email where I said that I'm interested in being an author. After that, we exchanged a few emails where they asked me about my experience with specific technologies. Then they shared a lot of documentation and gave me a topic for an evaluation article. Documentation I got was very detailed and it contained writing and coding guidelines, formatting standards, and a lot of useful info about internal processes. Since the evaluation article is all about your writing style and following guidelines from the documentation, be sure to really go through it. Later, this will save you from spending too much time going back and forth with editors.