What did the boss mean when he said he hoped we would have a chance to cooperate after the interview?

In fact, the boss already knows whether there are opportunities for cooperation. When to call means that we will continue to interview other people, and then we will choose the best one. But in general, such an interviewer will still consider leaving some space for the other party. If you like this job very much, you can still fight for it. I believe that opportunities are for those who are prepared. If you want to find a satisfactory job, you should work hard on your professional knowledge. It's okay to be professional during the interview.