Personally, I wouldn’t stare blind about the differences of 2.9 vs 3.0.
I would stick to the 2.9 version used in the course.
Most 3.0 features are nice to have.
But learn the basics first, which can be done in 2.9 and 3.0.
At this part of the learning stage, I think the difference between 2.9 and 3.0 doesn’t matter. Sure if you want to use 3.0 for faster or better renders using Cyles X, go ahead. But it’s not like 3.0 has a shed load of features that 2.9 doesn’t. It’s good to stay up to date with newer versions, but right now, just focus on learning new things and don’t worry about the beeeeest quality or performance. I’m still on 2.9 and people who have done much greater things than me have done it on older versions, so it doesn’t really matter until you get the experience.