Hello, I know this platform not gives source code of app, but can you please allow it after paid or something, we like to open app on android studio and add some advanced functions.
Thank You
The aia you can download is the sourcecode. If you want to develop further you should read the following topics.
Kodular is coding free platform, You have to use it and need to explore it because it is much easier than android studio, i think you have to shift to Kodular. 
I tried it but kodular new version seems not support for it
You can not use Kodular aia with Java Bridge. The builders are to different. And Java Bridge was made for an earlier version of App Inventor as far as i know.