Take a look at the Coursera specialization: Mathematics for Machine Learning [1]. The specialization isn't free but you can certainly apply for financial aid.
[1]: https://www.coursera.org/specializations/mathematics-machine...
[1]: https://www.coursera.org/specializations/mathematics-machine...
There is the financial aid and normally there is the option to watch the lectures and see the assignment for free. On the other hand, the cost of the courses rarely exceeds $50.