OK I got Studio. It is good, it can run all the stuff I wrote already with Classic. Now I have an Exporting Error.
It says:
Failed to read AndroidManifest.xml file.
And it won't write the APK because of this, also it seems to still be writing and APK, not the AAB I was looking for. Any ideas?
Edit. Looking up AndroidManifest.xml on google it says it should have been created when I created the Project. Could this be because I wrote the source in AGKClassic, but opened it with AGKStudio? Maybe I need to copy all the info; Source files, Media etc into a temporary place. Then delete the existing project and start again Creating a New Project with AGKStudio, then drop all the source and media into place again. Will try this and update later.
Edit2: THIS WORKED! I had to copy all the source code(s) to Notepad files, then copy the Media folder contents to a backup location, then delete the whole project in AGKStudio. Here I went to my Documents folder and deleted all things related to my old project, just to be sure. Then I opened a fresh AGKStudio, and created a New Project, added in all the source code(s) repopulated the newly made Media folder. Ran my game to see it worked OK - it did. Export to Google App Bundle. Voila! My game .abb archive file is there - now to publish before Google shut down my account.
Thanks for all the pointers. And keep an eye out for FlipX