my aircap is not snapping correctly even though i'm doing the same as shown in the lesson
Snapping can sometimes behave a little funky. In Blender 4.0 there was a great upgrade to tell Blender specifically where you want to snap to, you can see it on this video here:
https://cgcookie.com/lessons/pivots-snapping-and-proportional-editing
Sounds like your normals maybe flipped on your wheel. Which will cause the snapping 'align rotation' to be incorrect.
You will need to fix this or you will have issues later in the course.
Select the wheel and enable the Show Face Orientation Overlay, if the wheel turns red, then your normals are incorrect.
If this is the case, with the wheel selected enter edit mode, press A to select everything, then press SHIFT+N to flip the normals and the wheel should now be Blue.
The color of the face orientation overlay...
Red = back (internal) face
Blue = front (external) face
You will now have to move the origin back to the bottom of the air cap.
