Windows Defender reports that Urbackup Server 2.3.8 _exe is unsafe

Windows Defender reports that Urbackup Server 2.3.8 _exe is unsafe. Publisher unknown I believe was the message. Downloaded the file from Urbackup.org.
Windows 10 OS on an HP desktop. I’m just starting with Urbackup. I’m is the porcess of moving the server from one PC to another. I’m just trying to get good backups of 5 Windows computers on a local network.