Rejected because of technical problems

Para hacer fotos de este tipo te recomiendo usar un objetivo macro o usar tubos de extension, asi podras  hacer larga exposición y enfoque preciso con una buena profundidad de campo y bien iluminada, siempre con tripode naturalmente.

As Nancy indicated, it's not in sharp focus and is underexposed. In addition it's too closely cropped. Photographing and editing flower images is a good way to practice your skills; however, I wouldn't do so with the intent of selling them on Adobe Stock which is already saturated with millions of very high quality flower images. If you search the Adobe Stock database for "white+flower" 9.7 million images will be returned!