Welcome to the Make community!
You’ll need to right-click the trigger module and select where to start from.
If you selected “From now on”, only newly uploaded files will be detected when you turn on your scenario, and a “Check run” will occur every scheduled interval (default 15 mins).
If you want to learn more about Make, you can read up in the Help Center. I also recommend doing the tutorials in the Make Academy, and learn advanced skills like how to make custom apps to any API in the Make Partner Training Portal - both have certificates for successful completion.