problemas de calidad

The noise will be the most difficult issue to fix. You will also need to edit out any logos (like on the backpacks!). I doubt that you will be asked for model releases, however.

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

Noise and chromatic aberration. Zoom in on the people and the noise becomes evident.