To "expect" something is to think that it will happen. In the example above, "don't expect to get a high-paying job" means "don't think that you will get a high-paying job; realize that you might get a low-paying job"

When you use the phrase "expect to ___", the subject is both the person who's expecting, and the person who is doing the expected action. Take a look at this example:

I didn't expect to get a job offer so quickly.

In this sentence, the speaker ("I") is the person who didn't "expect" something, and also the person who got the job offer.

If the person who's expecting and the person who's doing the action are different, you use the structure "expect (someone) to (do something)":

I didn't expect him to get a job offer so quickly.