Unable to switch to the pop up window while uploading folder to Sharepoint

My task is to upload a folder to Sharepoint which has multiple folders with files residing in it. While uploading, a pop window appears and asks the user confirmation. My selector does not able to recognise the pop window. instead it was selecting the background selectors. I tried using attach browser, attach window but still does not work.

Can you try switching to modern design and try to indicate that?

It was already enabled. Not working…

@Madhavi_Puliraju
classic activities also you have tried