Trouble Downloading Your Certificate (Safari Browser)
Make sure you turn off your pop-up blocker so that you can download your certificate of completion on iPhone/iPads/Macs.
For instructions on how to turn off pop-ups on Mac computers, please check Apple's website below as instructions vary by operating system.
https://support.apple.com/guide/safari/block-pop-ups-sfri40696/15.1/mac
On your iPhone or iPad, go to Settings > Safari and turn OFF Block Pop-ups like this, then attempt to download your certificate again.