You cannot get the official Ascent course for free. But you can get the same skills, taught by the same caliber of artists, for free, if you know where to look. School of Motion and Maxon (the maker of Cinema 4D) have a symbiotic relationship—they want you to learn so you eventually buy the software or the course.
How to Level Up with Cinema 4D Ascent Ready to take your 3D skills from "getting by" to "pro-level"? School of Motion’s is the industry standard for intermediate artists looking to master professional workflows. Led by Maxon Certified Trainer EJ Hassenfratz , this course dives deep into the high-end techniques that separate the hobbyists from the pros. What You’ll Master in the Course School of Motion - Cinema 4D Ascent Free...
: Students use a custom platform to access lessons, receive critique from Teaching Assistants, and engage with a private community of peers. Cost and Access Options You cannot get the official Ascent course for free
While the "Ascent" course itself isn't free, School of Motion occasionally offers "Level Up" or "Pathways" webinars that provide a taste of the curriculum. How to Level Up with Cinema 4D Ascent
Their website hosts hundreds of free, deep-dive tutorials covering C4D, After Effects, and design theory.