If you're REALLY rusty (maybe you've been out of school for a while 5+ years), or maybe you just never learned the material that well in the first place, then you might want to start with one of our Mathematical Foundations courses that will scaffold you up to the level where you can handle the content in Mathematics for Machine Learning. More info can be found here: https://mathacademy.com/courses
The Mathematics for Machine Learning course would be ideal for anyone who majored in a STEM subject like CS (or at least has a solid mathematical foundation) and is interested in doing work in machine learning.