Why is it when I download apps, I can not access or use them?

[AC Question]

You can see that it was downloaded and its in a file, not on homescreen or anywhere is there the icon.

 

[hallux]

Where are you downloading it from? Downloaded from the Play Store, you shouldn't see it in a file in Downloads. It sounds like you downloaded from a 3rd-party app market, you would then need to install the app for it to show up in your apps list.