The flower is not sharp in focus. Large areas of the images are overexposed.
Yep, the focus isn't good, it is overexposed and composition can also be improved.
There are also a lot of flower photos these days, so yours will have to stand out from the crowd. It doesn't here. 😒
It's really important to review your photos at 100%-200% magnification. It's easy to see noise, grain, focus issues when you don't have the image zoomed out or on a small screen. As @Marianne-Deiters and @ricky336 pointed out your image is overexposed and lacks focus. Take a look at this snippet at 100% magnification - you will see the water drops have blown out highlights and no sharp focus. Also look at the green background - there are a lot of artifacts and noise in your image - it could be from over sharpening.
Take a read through some of these resources that you might find helpful.
As was mentioned earlier there are millions of flower photos on Adobe Stock. Flowers are still a great subject to practice your photography skills and techniques. If you do get your flower pictures accepted, don't necessarily expect them to be great sellers for you just because of the volume of images to which you'll be competing. But then again, if you can capture something creative and unique, you'll get your sales.
Best of luck in your future submissions.