Android has moved to a file system model that generally locks app out of having full control of any folder but the one created for the app. The only way to let your app have read-write-create permissions is to request access to the whole file system. And IIRC, you have to get permission from Google to even request it.

It makes it very difficult to have something like a Git client on Android as well, as the permission to request file system access is not easily granted.