Others have experienced the same, no email, and used the direct link to do the test and they were fine. When you called IRCC did they confirm that your email address on file was the correct one? Do you have a representative? if you do the email may have gone to that email address. Otherwise, try to access the direct link and if it opens up the access to the test you should be fine, but if you receive the error message below, then you need to keep calling IRCC to verify the access for you.
Based on our records, we haven’t invited you to take this test right now.
You can’t take the test right now