Welcome to the community. 
This is usually an indication that there is a security program on your PC or WiFi network blocking your connection to WeMod’s servers.
But before we get there, first thing to do is to try restarting your router.
Turn it off. Wait 30 seconds for the WiFi signal to completely dissipate. Then turn it back on and try WeMod again.
If that doesn’t help, then this post might: I can’t Install WeMod / "There was a error installing the application" - #2 by Ravenfyre