Don't worry! This does not mean you were rejected.
Companies usually send out the SHL test 1-2 days after the candidate applies, and forms part of the pre-screen. This means that nobody at your firm has reviewed your application yet. The results of the SHL test will be used together with your Resume/Cover Letter to review your application.
Therefore, once you complete your test, it is not at all unusual for there to be a larger wait time to hear back - this is the time it takes McKinsey to review your application. The firm won't respond with the results of your test - they will just reply once they have made a decision whether they would like to interview you or not.
Good luck and don't worry!