Hi Daniel,
So two things might be happening there:
1 - not quite sure that wix url is working because of the way adobe embed api processes data, I suggest testing other like gdrive direct link (https://drive.google.com/uc?export=download&id=FILEID ; you get file id from your sharing link), or even adobe url used for testing “https://documentcloud.adobe.com/view-sdk-demo/PDFs/Bodea Brochure.pdf” just to see if its related.
2 - Most important check if filename is “undefined” - if so that is what’s causing the error, because adobe embed cant process de file without it.
Hope this helps!
Cristina