One of Superman’s known weaknesses, besides that of kryptonite, is that he’s as vulnerable to magic as the average human (besides what he can avoid with his super-reflexes).
So why doesn’t he learn to use magic? His Super-intelligence and speed would make it much easier for him to learn magic compared to the average person, and he’s already well aware that magic exists.
Knowing magic would help him cover a major weakness of his, so it seems illogical that he doesn’t pick it up, or look into it.
Magic is a bit vague force/phenomenon in DC. While some characters know how to use it, others don’t. The question you raised applies to many different characters, including Batman, so we may assume, that it takes some special “natural affinity” to learn it in this specific universe.