So I tried to install using auto-updater but failed, so I went to the webpage and download the latest installer.
MultiCommander_x64_(15.4.0.3088).exe
MD5: 140a68bf6c281779e0838e044d614ec7
https://www.virustotal.com/gui/file-analysis/MTQwYTY4YmY2YzI4MTc3OWUwODM4ZTA0NGQ2MTRlYzc6MTc0NDg4MDAxMQ==and clicked on upgrade.
It seems that Microsoft Security Essential is detecting it as a Virus: Wacatac.
Likely a false positive, worth to investigate in case it is not, and also to see if it can be done something to remove the false positive, whilst I can uncuarantine at home, I won't be able to do that at my work computer.