composer require zburke/flysystem-box
Assuming you have a valid bearer token from an oAuth2 authentication session:
use Zburke\Flysystem\Box\BoxAdapter;
use League\Flysystem\Filesystem;
$adapter = new BoxAdapter('oauth-token', [$prefix]);
$filesystem = new Filesystem($adapter);
To generate a temporary developer token, visit https://app.box.com/developers/services/ and click the "Edit Application" button for the app you want to use, then click the "Create a developer token" button.
If you believe you have found a bug, please report it using the GitHub issue tracker, or better yet, fork the library and submit a pull request.