Epic Games Launcher crash at start up right after logging in [ Didn't download UE4 yet ]

sorry about that, i should have enclosed it : start CMD
go to the catalogue where Your install file is.
type the command : msiexec /i fullinstallfilename

What i would suggest to find out if you have a profile issue. is to create a New user on Your system.
login as the new user, install launcher and see if it Works then.