I was using it yesterday and everything was normal. But today it appeared.
Plz help me 
Welcome to the community. 
This is caused by your antivirus program or your network security.
Please use the search button before posting, this has already been resolved multiple times, so you’d have gotten the answer in seconds.
See here: I can’t Install WeMod / "There was a error installing the application" - #2 by Ravenfyre