Mainly the photos are not well focused.
Focus and exposure.
In addition to what the others have said about focus and exposure, I would also say the photos are overprocessed. The colour saturation is too high and the photos don't look natural. There are also a lot of artifacts and colour noise in the photos. It is always recommended to review your photos at 100%-200% magnification. It is much easier to see errors and issues in your images then.
This is at 100% magnification and you can see the halos around the flower petals in the middle and the artifacts and noise all over the image. It is much easier to see the lack of focus on the flower petals as well.
In this image the noise and colour noise are very noticeable in the background.
To quote Adobe Stock requirements "For your images to have commercial value, they shouldn’t show noise or dust and they should be well-composed, appropriately lit and exposed, and processed in an inconspicuous way. "
Here are some resources that you might find useful:
As a general comment, flowers (along with sunsets, sunrises, pets) are very well represented in the Adobe Stock database with millions of great photos in each of those categories. Floral photographs are a great way to practice your skills of photography, composition, exposure and post processing. Just be aware that if you do get these images accepted, the competition is pretty fierce already and they will probably not be big sellers for you.
Best of luck in your future submissions. I hope this helped.
The flower photos aren't that interesting - sorry! They have to stand out from the other gazillions of flower photos on stock. They need to have the 'WOW' factor. These photos unfortunately lack that!
Have a read of this from Adobe about how to create better photos:
If you are new to stock, you should consider these resources: https://helpx.adobe.com/stock/contributor/tutorials.html
Please read the contributor user manual for more information on Adobe stock contributions: https://helpx.adobe.com/stock/contributor/user-guide.html
See here for rejection reasons: https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
and especially quality and technical issues: https://helpx.adobe.com/stock/contributor/help/quality-and-technical-issues.html