For the pre-screen, they use Code Signal. This platform provides four randomly picked problems that you can solve in a programming language of your choice within 70 minutes. The primary challenge lies in the randomness of the problems. While the problems themselves are not very difficult, you might encounter four complicated or lengthy ones, making it challenging to solve even one. Even with some luck, most fresh graduates tend to solve a maximum of two.

You can train and even take the pre-screen for free. You can retry it every two weeks; I recommend doing that. You might get lucky and receive easier questions and a decent score. If you are applying for this position, you will be required to complete the pre-screen. However, if you have already completed it, you do not need to do it again.