If you are unable or having difficulty downloading a certificate for which you were approved, here are some steps you may to take to resolve this.
First, check that the certificate has been approved and is not still in pending status. You should be able to see an "Approved" status as well as a "Download Certificate" or "Re-download Certificate" button on your record in My Matches:
Once approval is confirmed, where the certificate is downloaded on your computer will depend on your internet browser's settings. Depending on your settings, common places are either the desktop, a "Downloads" folder, or another designated place, as determined in the "Preferences" settings.