Possible third party side-load tools are listed in links below, but direct integration is preferred:
** https://webapps.stackexchange.com/questions/55191/how-to-save-a-file-to-dropbox-using-an-url-to-that-file
** https://www.makeuseof.com/tag/5-ways-send-files-dropbox-dropbox/
** https://medium.com/savetodrive/easily-upload-a-file-from-a-url-to-dropbox-8e5bbe9ae1e,
** https://www.dropboxforum.com/t5/API-Support-Feedback/Is-there-a-Upload-widget-that-I-can-embed-on-my-site/td-p/77192 - 2015 list,
** SideCLOUDLoad seems to be on several recommended lists
