Having trouble finding the track z camera tool

That tutorial has 350 thousand views and I would give the workflow a C and the recommended use of the UI a C-.

If you are using CC 2020, the toolbar has changed. You can still press the C key multiple times to step through the different camera tools, but manipulating the camera with these tools is quick but fairly inaccurate. If no layer is selected, the new unified tool will move the camera or change the view, but the C key still steps through the same options.

Using multiple views and grabbing the actual X, Y, or Z handles on the 3D cursor with the 3D tools set to local axis mode is by far the easiest way to manipulate the camera. 

I hope this helps.

What tutorial? There is no Track Z Camera Tool, but there is a Z-axis on the camera that you can grab and move. The way the camera moves depends on which orientation you have selected for the tools in the toolbar. I prefer Local Axis mode. It is the first one and it allows you to move the camera directly toward or away from the Point of Interest when using multiple views.

Beware sceptical of the tutorials you look at. Most of them are prepared by well-meaning enthusiasts and they are poorly explained, many have inefficient workflows, and quite a lot of them are just the wrong way to go about something. When you have problems with a tutorial it is important that you post a link so we can know what you are trying to do.