I've tried to figure it out myself, but I don't know what to do. I'm trying to make 300x600 banner size, but when i put image i want into that file, the quality is horrible.
Checkout the image in full resolution and check it in my PS..
I don't really use Adobe Stock, but it seems likely that they will have higher resolution versions of those images. Perhaps at a higher cost. Is this banner for a website, or printed page? If the latter, how big?