Showing Score Upon Submission
Certify'em only shares a certificate if the exam-taker passes your exam. No notification is given by Certify'em if the exam-taker does not pass, and the same message is shown to exam-takers upon submission regardless of whether they passed or failed.
You can, however, update your Google Quiz settings to share the score in points (e.g. "5 / 6") immediately upon submission. Combined with a custom message shown upon submission (e.g. "You need to have scored at least 5 / 6 to pass and receive a certificate"), you can give exam-takers an indication of pass/fail.
To show the exam taker's score upon submission, adjust your Google Quiz settings as shown below:
Upon submission the exam-taker will see your message, and a "View Score" button.
Clicking the "View Score" button will take them back to a copy of their exam submissions, with their "Total points" at the top: