I didn't watch the tutorial, but any tutorial that tells you to auto-weight/auto-rig something is typically wrong. You'll want to do all the weighting manually.

How do i do that?

OK, so first ask yourself if this is in the scope of being new to blender (I wouldn't start off animating unless I knew what I was doing).

Having said that, I should mention that I might not be the best person to ask about this specific problem since I don't typically do complex bone rigging for animations, but essentially you'll want to look into weight-paint mode for rigging models. It's a huge learning process in itself, and you should look into rigging if you want to learn animations.

This video should describe the basic process, but again it's something you have to learn over time: https://www.youtube.com/watch?v=S0VS0IVylzg