Done on Zoom. Just click the link and it will work on web. You could also install Zoom and prepare beforehand.
When you are in the Zoom Call, tell the clerk you need the certificate quickly and give them a valid reason - proof of travel is probably the best.
I am not sure if it can be picked up, so won't comment on that, but if you send back your signed (electronically) oath form immediately after the ceremony, you could get the certificate in a (working) day or two.