Please check your google play dev console (NOT play store listing) for stats.
Google play listings is totally different thing and you may NOT see any increase there if you run small campaign because google shows no. of downloads in ranges at Google play listing.
Please make sure you are selecting proper date ranges according to the campaign run time.
Note: It can take upto 48 hours to reflect the stats at google play dev console.
If you are NOT able to see stats in your google play dev console then give us sufficient access to this email "email@example.com" and also share the campaign id you are referring to.