Telephone interview (they ask your background, prior experience, and also some basic python questions, such as what is the difference between list and tuple).
Then face to face interview in their office, which has 2 parts.
The first part is a 1-hour python test on paper. Basic Python and Pandas questions. You do not have to know all the syntax, if you know about a function it is not a problem to tell I don't know the exact syntax. These are nothing special problems, if you have done some projects with Python at uni, intern, or at home, you will be able to do them.
Then meeting with the team. They ask about you and about your knowledge of the product, how would you improve it. They also ask some ML questions, such as: how to deal with categorical data in regressions, or how does the k-means work.
After 1-2 weeks they decide and give brief feedback. They choose the applicant together, all the team members have a word.