Most people have trouble Crediting art
The Rules.
If the artwork was created by you or an artwork generated from royalty free image to create something unique by you then put your name in the Table and on the card Image.
If the artwork is royalty free and/or public domain then no credit is required on the card image but in the table put a link to the source.
If the artwork is Copyright to the artist then the card image requires the artist name and the table should have the artist name and a link to the source location.
If you can't find an artist name then a link to the source is mandatory.