Unfortunately, we can no longer claim WaterWoo (or WooCommerce for that matter) will work with Dropbox-served files using the WooCommerce Dropbox plugin. It was brought to our attention that files are not being reliably served intact to WooCommerce from Dropbox by the plugin. Since support for the WooCommerce Dropbox plugin seems to have gone away, and the plugin hasn’t been updated in two years, we recommend you use another solution for hosting your files externally until the Dropbox/Woo plugin is repaired or a new solution becomes available.