How To Get Camera To Rotate Around Player

Here is the youtube video I was watching for reference

If you skip to 6:10 you will see the SerializeField I’m having trouble with

But I noticed on this tutorial they’re using an older version of Cinemachine. I’m sure this may have something to do with it, since line 6 I had to alter
putting, using Unity.Cinemachine; because, using Cinemachine; could not be
found.

What code am I missing or can I implement to fix this issue?