Is home training with YouTube videos enough or do I need a gym?

Forget the idea that you absolutely need an expensive studio - that's just not true. YouTube videos are completely enough to get started and make decent progress too. Most free or cheap channels have decent production quality these days and show you the movements clearly enough. As long as you have a flat floor and maybe a yoga mat or some space, you're good to go.

The problem is, though, that you make mistakes way more easily when training at home because nobody's there to correct you. When you do YouTube videos, you can see what it's supposed to look like, but whether your form is actually correct, you often don't realize until something hurts. For absolute beginners that can get annoying because you get frustrated pretty quickly if you can't nail the exercises.

My tip: start with YouTube, check out several channels and pick the ones whose explanations help you the most. After a couple weeks you could maybe do a single session with a trainer just to have them check your form - doesn't have to be regular. That's way cheaper than a studio membership and afterward you'll know if you're on the right track.