My downloaded items are in .ds_store and .key extenstions files but unfortunately not able to open in windows 7 please help.
Those are Apple file extensions.
It doesn’t matter what version of windows you are running, they won’t work.
You need Keynote to open it which is Apple only. There is probably a Google slides or PowerPoint version of whatever item you bought for windows users
You can ignore and delete .ds_store files
.key file should be opened via notepad