As PIAs used, we understand office installation is required. Can run the code without office installation?? or only VSTO enough?
Yes, Office must be installed on the system to be able to use automation. VSTO is a framework for developing Office COM add-ins. They don't make any sense without Office installed on the system.
Our code is hosted on AWS cloud
Microsoft does not currently recommend, and does not support, Automation of Microsoft Office applications from any unattended, non-interactive client application or component (including ASP, ASP.NET, DCOM, and NT Services), because Office may exhibit unstable behavior and/or deadlock when Office is run in this environment.
If you are building a solution that runs in a server-side context, you should try to use components that have been made safe for unattended execution. Or, you should try to find alternatives that allow at least part of the code to run client-side. If you use an Office application from a server-side solution, the application will lack many of the necessary capabilities to run successfully. Additionally, you will be taking risks with the stability of your overall solution. Read more about that in the Considerations for server-side Automation of Office article.
You may consider using third-party components designed for the server-side execution instead.
