How to help users to download and install native app

I am planning a landing page for downloading an app. I'm afraid that for some of my users it will be the first time they are downloading a file.

What is recommendation for helping users to understand that the next step is to click on the downloaded file?

I have read this: How to make file download progress more obvious. But my question is how to help the user understand that they need to click when the download finish.