android app dont start on device after inistalation

It could be a number of things, like any platform (Mac, iPhone, Windows), Android also has OS's, like windows has Windows 7, Windows 8, Windows 10, and some things dont work on certain versions, the same goes for Android, so you need to make sure its all compatible...

First check that your API library is at the latest, I BELIEVE that is Version 23 (I could be wrong on that), and that you have a reasonable Minimal Version set in the Player Settings for Android.

Completely uninstall the application from your phone, then add the APK file (however your doing it, manually, or through a website, etc), but before you actually install it, because your testing it, and your a 3rd party developer, youll need to go into your phones settings and enable "Allow 3rd party applications to be installed".

Once you do that, then try installing it from the application on your phone. It should successfully install if everything is set up right.

At that point, you should be able to tap the application, and it should run fine, assuming that the code itself in your application is built right and their not trying to load a ton of things at once (any mobile app is not meant to be super intensive with events and actions and stuff, it doesnt have the same power a computer does, I only bring this up because that may also be a problem, your trying to for example spawn 7000 objects at the start or something super intensive that doesnt need to be there for a mobile game)