Multiple users, restricted access

Hey, folks, I'm new to this side of things, and I'm hoping someone can help me out.

I just signed up 5tb of storage through Hetzner's storage share, using nextcloud. I like it so far, but I'm running into an issue. I figured out how to make multiple users, but I don't know how to (or if I can) restrict different users to specific folders. We're broke, so this is going to be shared between me, my mom, my brother, and my sister in law. If it's possible, I'd like to create a folder for each of us, and restrict access to that folder to just that person. I don't want to be able to see what's in my brother's folder, and I don't want my mom seeing what's in mine, et cetera. I've tried to google it and look it up on youtube, but most of what I can find isn't related, and if it is, it's a bunch of technospeak that I don't really understand about self-hosting, which I'm not doing. If it's possible, it would be cool to have a central shared folder as well, but we could just share links with each other when we want to share something if needed.

Any help is really appreciated. Thank you in advance.