How did you uninstall it and download it. Is it rooted?
As Javier said if you search for something in Google Search Google Now it generally opens in a Chrome browser, I think. You may want to set the default browser to Chrome to see if it comes up from a link.
There should be a default applications setting in Task Manager, I have a Galaxy Note 3, or you could Rsset App Preferences (all of them) in Applications Manager - Menu.
You sure it's not in your app drawer.
When you say it's showing as installed, do you mean Play Store shows that, or it's showing in Applications Manager - All, or both.
Why not empty all folders, put the app drawer in alphabetical order, and post a screenshot of the C's.