Not certain what you are trying to do here. Kodi uses "add-ons" not apps. Android uses apps. Most Kodi support sites have instructions on how to locate and install add-ons.
Apps installed from Google play normally auto install. If you get the apk from somewhere else and download it, normally you would find the apk in the default Android download folder then click on it to install.
If you are trying to install Kodi itself then the best place to get it is Google play store and it should auto install from there.
