Technische Probleme

Welcome @Dagmar21784563zyqq , there were sensor / dust spots that I noticed right away on your image.  Look in the upper left corner and to the right of the sun.

The sky also has some noise, which would look better if it was smoothed out.  I would also suggest you remove the airplane trails (they distract from your sunset) and also remove the birds that just look like black dots around the treeline.  I also think the light reflecting on the rocks should be gone as well.

Generally, the white balance is a bit off and is too yellow, in my opinion. While not off by much, the horizon needs to be levelled as well.  While the reflection of the sun on the water is blown out, I don't necessarily think that is a major concern.

Generally, I like the silhouette of trees and the dock.  I think it is a good composition and you should be able to make some edits and resubmit it.  As a side note, I will mention that sunsets (along with flowers and pets) are heavily and well represented in stock photography.  I am by no means saying don't photograph these subjects or submit them, I just want you to be aware that they may not be very good sellers for you as there is lots of competition already.

Here are some resources that you may find helpful:

• Requirements for images - https://helpx.adobe.com/stock/contributor/help/photography-illustrations.html
• Reasons for rejection - https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
• Quick start guide for contributors - https://helpx.adobe.com/stock/contributor/user-guide.html
• Tutorials for contributors - https://helpx.adobe.com/stock/contributor/tutorials.html

Best of luck with your future submissions.  I hope this helped.