Frodev You should first make a simple movement setup with a fully static camera that doesn't follow the player. This should give you some fundamental insights on how to work with 3D vectors and basic kinematic movement in 3D. You'll see that this part is very similar to 2D. After that, add a simple third person camera follow to the setup, without any camera rotation. And after you get this to work, add some camera rotation to that follow. And finally you can tune the whole system to look and feel good for the player, by adding smoothing, easing, transitions etc...
When coding, always try to divide a problem that looks overwhelming into simpler sub-problems, and tackle one by one, gradually building the system from a simple start towards more complexity. You can divide as much as needed until every part of the big problem looks trivial to solve. Then just add all those simple solutions together and voila - you solved the complex problem.
There's a reason why the whole thing is called game (or software) development - you gradually develop the thing 🙂 In the process, you also develop your knowledge and problem solving abilities.
Otherwise you'll likely never understand what you're actually doing and will always depend on some premade code that you have no clue how it operates. In the long run, it'd be very hard and frustrating to complete a game working like this.