Create a key store (.jks file) with an upload key (a private key in key store), using Android studio
Build a Android Application Bundle (release/myapp.aab). This file is signed by upload key
Upload myapp.abb to to Google Play Store.
During the first upload, the upload key public key is stored and used all future upload.
Google play also generates an App Signing Key (which is stored only at Google)
Google Play split abb and build APK files. Sign it with App Signing Key