Hi! Thanks so much for the kind words — I’m really glad you’re finding the card creator useful.
Just to double-check how things are behaving on your side: the Assets library starts out empty and is populated with images that you upload yourself. Once images are uploaded, they should appear both in the Assets view and when selecting an image for a card.
Were you able to upload any images yet, or does the library remain empty even after uploading? If it’s the latter, that definitely sounds like something I should look into.