The Camera does not have material options, it has camera settings. You need a 3D layer to have material options.
Start a new comp.
Add a solid or create a shape layer or add a text layer
Make the layer 3D
Select the layer you have created and press aa to reveal the material options. Material Options are only available on 3D layers and some material options are available if you use the C4D rendering engine and others are available using Classic 3D.
Watch out for tutorials prepared by enthusiasts that don't really know what they are talking about. If you are following a tutorial and you get lost the chances are that the tutorial isn't a very good one. The best place to learn how to use AE is the User Guide. There are tutorials on working with 3D layers there that will walk you through the process in a way that develops good workflow habits.
If you don't see anything then post a screenshot showing everything you have done in the comp by selecting all layers and pressing the U key twice. Then embed the screenshot using the toolbar in the forum, don't just upload it.