It's very underexposed and blurry. Did you use a tripod ?
Yep, as @Jill_C mentioned, you have exposure problems, and it seems like camera shake. The camera moved slightly during the exposure. The result is it is not very sharp.
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General, not specific advice... There are many amateur photographers submitting to Stock, and doing well. But they must submit work as good as an experienced professional. Adobe want world class commercial photographers, made by people who fully understand the techniques of great photography. In some ways this is a great photograph, I must say. But what I mean is that it's a photograph of a great place, a great moment. But the photograph is not technically great, and Adobe insist on that. You need to be fully aware of how to work with your equipment, and when it can't do the job. You need to be aware of exposure and lighting, when and how to work with RAW, focus, depth of field, colour balance, noise, lens issues, and more. You need to know how to examine your work, pixel by pixel, to make sure it is perfect, or if it is not perfect, whether and how to fix it. You need to have a true eye for a great composition, and how to set up your shots to be the best possible. Successful stock photographers are likely to have been enthusiastic hobbyists for years - but which I don't just mean they have been taking photos for years: extensive technical training (including self training) is a must. Good luck, with turning great moments into great photography!