I very much echo RC here. You should be using a SOTI Package that encapsulates the APK rather than trying to push it through an App Catalog. SOTI Packages give way more version control and assignment scheduling capabilities than Managed Google Play Private apps or App Catalog Enterprise apps. As long as you always build from the same Package project, increment the package version, increment the APK build version with each compile, and sign the APK using the same mechanism every time, then you can install new versions of the APK on top of each other with direct upgrades with packages.