I got an online assessment which consists of 3 parts: Statistics Concepts, SQL and Python (mostly sklearn and pandas libraries); 36 questions in less than 90 minutes. Difficulty seems to adapt depending on whether you get the questions right or wrong.

Initial Coding Hackerank test (3 Questions, one simple coding question, one encryption question, one time series LR question) and a QuantHub test. Two rounds of interviews, 3 in the first, and 2 in the second. Consists of personal experience, technical experience, case scenario, and technical questions (ROC, Linear Regression, Random Forest, regularization, feature selection, etc). You know in advance what the interview type will be, eg they'll tell you it's a case scenario and personal experience interview. They provided you with a lot of info before you start the process and there is a lot of prep on their website (especially for the personal experience section, DON'T NEGLECT IT!!). The hardest part is getting the interview, once you do, MAKE SURE YOU PREP!, and you'll be fine.