You could use the sftp module. Import, add module role(s) to your system userrole(s) and add the configuration snippet to an admin page in your app, like the documentation for this module says.

In your microflow, get the SFTP configuration for your SFTP server and use the put file action from the module to upload your file.

After restarting your app, configure the SFTP settings for your server as admin and you should be good to go.