General overview of sharing a whiteboard from an iPad:
Log into Zoom from the iPad and become the "Host" on that device. Then log in to Zoom on your PC or Mac at the same time.
You can then share the whiteboard from the iPad. Students will see your webcam at the lower corner of the screen with the whiteboard being the primary shared content.
Mute the audio and microphone on the iPad. If you do not you will get reverb from your PC or Mac.
A good stylus is suggested when using a whiteboard. If you're using an iPad, the Apple Pencil is a great tool for drawing and writing.
You can create multiple whiteboards (essentially, multiple pages), and save them as images after the lecture. However, if you close the whiteboard before saving, you will lose all of your data and it cannot be recovered. So be sure to save the whiteboard first if you want to keep the information.