Is it possible to export documents or other content from SharePoint online using a workflow (or other method) to an external location?
The recipient will likely be an ftp location, and won't be an email address - the idea is to have a daily export.
I would suggest to use power shell with CSOM for SharePoint online which is the best and efficient way to handle these kind of automation's.
overall solution will be:
writing a windows powershell script leveraging CSOM for accessing sharepoint resources and then connect to FTP/SFTP to trasfer the documents.
finally, schedule this script as a task with in the task scheduler of windows server.
You can create a Microsoft Flow that run each time a file is created or modified to copy it in a FTP folder.