Yes, the APK should include all the files you need – there’s no need to install Ministro.
After you check your settings again to bundle the Qt libraries in the APK, can you please try this:
Delete the build-folder and then run the clean and qmake commands (right-click on the project), before you do a new android build?
This will lead to a completely fresh build, that hopefully correctly packages everything.
Alternatively, you can also try using the Gradle Build System. Maybe removing the Android Kit from the project and adding it again can also help.
If nothing of the above works, can you try to deploy a new, empty demo project? Does the problem also occur for this project?