Bit of a noob here. I was wondering if I have to subscribe to a cloud storage service to use filepicker.io.
You do not have to subscribe to S3 to use Filestack, however your app gets a lot more powerful if you do. Thanks to that, you can store your files directly to your storage so you will never lose access to them. If you haven't put in your storage credentials your files will be stored on Filestack's server.