Sometimes the Settings page may loop after claiming a certificate.
Try pressing the back key to get back to the learn page.
You should see a message at the top of this page, as @Sky020 mentioned.
From there, go to your profile to see whether the certificated is listed under the points heat map.
In the Timeline section you’ll get one list item for it when you pass the certificate, and another one when you claim the certificate. You may need to navigate using the arrows to get the correct page.
Go back to the Settings page and click on the claim certificate button, if you haven’t done this. A message will appear at the top of the page congratulating you on your achievement.