Hey @Cuong,
User on Volumio-OS is static/predefined: volumio (username must not be changed, password must not be changed, or your Volumio-OS system will be broken)
With FileZilla your connection protocol schould be sftp
Although it is possible, use of this method is discouraged, where the most prominent obstacle is that the media assets must be owned by UID:GID = nobody:nogroup.
For this reason the Volumio-OS uses smb/nmb (Samba) as file transfer daemon.
Kind Regards,