I'm trying to run an Bookbub Ad but I have run into a problem. They ask for an image size of 300 x 250 pixels, which is ridiculously tiny. All of my ad work is massively larger than this and reducing even a simple book cover for the ad destroy the quality completely. I can't create entirely new covers for an ad, so what is the solution? Am I missing something here? That's possible, I'm not tech at all.
Thank you.

Thank you.