The sources and advice linked below are helpful. Given that we have no idea what level "from scratch" means, or your preferred learning style, I'm upvoting Khan academy on the basis of their map/pathway/dependency graph. Shows how topics build on each other and gives you a framework.

The other piece of general advice is to define what it means to learn math. You only learn math by solving problems with it. Do the exercises. The theory is only there to enable you to do the exercises/problem sets.

preferably on paper and pencil (yes even for sets of differential equations where you have to track 14 complex variables over multiple steps and you fuck up your answer because you mis-copied an exponent on line 12 of 35 lines. It is slow and difficult on paper, and that is an advantage when you are learning).

[Warning Advice from a Beginner]

I started self learning Maths (number theory) this year from scratch I am extremely slow but I am progressing. My advice is take a textbook of the kind of maths you want to learn and skip the theory jump straight to the exercises do them and compare the answers, if your answers are wrong then read the theory. Also when doing exercises you can reference the theory but don't read the theory alone.

One thing that will block you is notation, if you are a coder Math As Code [0] is great way to decode the advanced Mathematical symbols, It helped me start reading math:

[0]- https://github.com/Jam3/math-as-code

This[0] was posted up on here a while ago - has some good book recommendations for teaching yourself maths (assuming you remember some basics from school[1]).

I got a few of them and whilst they may have gathered some dust... They seem great! Also obliged to recommend Khan Academy and the 3Blue1Brown youtube channel - but they are probably best for fun/inspiration

[0] 'Mathematics for the adventurous self-learner' -https://www.neilwithdata.com/mathematics-self-learner

[1] If I knew zero maths I'd probably check out the basics on Khan Academy or maybe get a tutor

It might help to clarify what type of Math you want to learn. E.g., right now I'm learning discrete math to improve my understanding of algorithms.