Many recruitment information says that electronic engineers are required to know auto cad. I don't know what role this software plays as a circuit designer. Please give me some advice.

Because AutoCAD can be used to design electronic circuits, it means that you sometimes need to make boards of different sizes. In fact, this software is of little use in developing hardware circuits. Sometimes the requirements written by recruiters may not be necessary even if you go, but it's no harm for you to learn. If you study hard, you can start soon.