No, it's not possible to use the Chooser without user interaction.
The createTemporaryDirectLink method in the PHP is a good alternative then. It returns a link just like the "direct link" type from the Chooser, but can be used completely programmatically. You can then download the file content via the returned link.
Can you share the code that's not working as desired?
Each call to createTemporaryDirectLink will make another network request, to get the requested information from the Dropbox API, so unfortunately there will be a good amount of overhead for that. I'm afraid I don't have a good solution, but I'll be sure to pass this along as feedback.