To improve myself and my quality

For detailed answers, you need specific questions. general questions can only get general answers. 

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

To clarify meaning, are you asking about Adobe Stock as a customer or as a potential Contributor?

• Customers buy assets for use in commercial projects.
• Contributors create assets for customers to buy. 

Read the Stock Contributor User Guide below for more details.

https://helpx.adobe.com/stock/contributor/help/submission-guidelines.html

I already sent you a link.