How do I save a non-media file (txt, csv) in one of the Shared folders and read it on Android 11+ ( and fix beginners bugs)

In case you hadn't noticed, AI2 has a spreadsheet component, to work with Google Sheets, and online Excel equivalent.

That would avoid a lot of file sloshing back and forth.

To add to the confusion, I have a similar app, just for personal use. To export and import CSV files, I use Dropbox. You can export your file using the Share component Social
Then, if you give your file a fixed name, you can make a sharing link for it and read the file back using Web.Get
So many possibilities!