I would like to know if this plugin can capture the window I want to capture.

Please use the tester application to check before purchasing the WindowCapture2D plugin.
This application is created using the WindowCapture2D plugin, so any window that can be captured with this application can also be captured with the WindowCapture2D plugin.

You can download the latest tester application (WindowCapture2DTester_vx.x.x_UEx.x.zip) from the following page.
https://github.com/ayumax/WindowCapture2D/releases