If I'm understanding your post, you have an apk that you are unable to install. Attempts at installing result in an option to cancel the installation attempt but no option to install. If this is the case chances are you have downloaded an app that is not compatible with your device. Look for the app again and try to find one that is compatible with your device. If you can go the the app's webpage and see if they offer direct downloads, or in your search query include your device and OS.