sFTP App is a file-transfer client and server for Windows, macOS, and Linux. The protocols it supports are SFTP, FTP, FTPS, and WebDAV.
SFTP is the SSH file transfer protocol. FTP is the older file transfer protocol. FTPS is FTP with TLS. WebDAV is the HTTP file protocol. Pick the one the server already expects. The client can also open an SSH terminal, use a built-in editor, and connect to cloud services including S3, Drive, Azure, and OneDrive.