I got the same issues installing construct. Avira popped up a warning when it was installing but I ignored it. I think this is a false. The exe file did not throw a warning when I downloaded it only when I ran it and it started installing. Usually if the exe has a virus it will pop up on the spot rather than allowing the exe to run before warning you.
Just tell it to ignore or add it as an exception or whatever avast calls for to permanently ignore it as a threat since it is not really a threat.