WIth the July 2021 release of Firefox 90, the FTP protocol handler will be completely removed.
You will need to either use another browser (Chrome, Edge, Safari, etc.) or the web (https) version of the download site, or use an FTP app, like WinSCP or Filezilla.
As for uploads (logs, sample files, etc.), is there an alternative URL/method?
Perhaps upload instructions should be updated to note that Firefox does not support FTP required for uploading log and video files for support.