First ensure that the logged in user is associated with the right ingest profile with (FTP or Network).
This can be managed under "User Management" section of Admin Tools page.
Feeder uses http/https to connect to the eMAM Gateway and FTP, UDP or CIFS/SMB to upload the files. We have noticed most upload issues with UDP and CIFS/SMB configurations. Please ensure that, the user's machine got network access to the ingest folder.
Also check if the Enable SSL option is checked. If yes, disable it.