Don't let this worry you too much - plenty of successful consultants come from STEM backgrounds, and there's less overlap between casing skills and college business/econ classes than you would think. Case interviews also do not require too much business/industry knowledge.
I would advise you to do the following:
1. Read the standard intro to case prep books such as Case Interview Secrets or Case In Point. They aren't perfect, but they do contain a lot of the background information that is useful to know for case interviews. Reviewing some of the common frameworks may help clarify some of these business terms too.
2. Reading/watching industry news. There are plenty of good resources on this: podcasts such as The Best One Yet (formerly MarketSnacks), newsletters such as Axios Markets and Axios Macro, or the good old Economist, Financial Times, Wall Street Journal.
3. Practice cases, even if it feels a little uncomfortable at first and you feel like you don't know enough, practice makes perfect, and the sooner you start, the better.
4. While you do this, be sure to clear up any confusing terms that you encounter along the way! This is the key to overcoming your challenge, in my opinion. I would dive in as elaborated in points 1-3 above, but whenever you come across a term or concept that you don't know, be sure to look it up. Then write it out, flag it for yourself, or do whatever would be most helpful for you to remember it. There's no perfect course or perfect way to learn these terms, so my advice would be to dive in and pay attention to what seems confusing, and then clear up any confusions as they come up. You may just be surprised by how quickly you start getting the hang of things yourself!
Best of luck, and feel free to message me any more questions - I have worked with many STEM candidates who successfully navigated the recruiting process.