What is the launcher?

[Floundogg]

This is not a defamatory thing or anything, just geniuinely curious and concerned. I downloaded the new witch launcher since I was prompted to come update it. I didnt initially disable antivirus or anything because I figured it would be about the same process. When I did download it, my firewall flared up with notifications that there was a trojan virus contained in one of the files. I tried reloading the site and downloading it again and again, preparing to launch it and it kept getting deleted and isolated as a virus. Can yall explain this a bit to me? I am actually wondering what makes the mods tick and if its safe. It would be nice to hear some transparency since it gave me a little scare. I haven't retried the mod launcher since.

This was the message it gave me: 

Detected: Trojan:Win32/Wacatac.C!ml