I believe you can directly execute an msi package through the command prompt and have it create a log file that may give you more information.
In the directory containing your msi type (change the file name to whatever yours is):
msiexec /i EpicGamesLauncherInstaller-2.12.6-3075554.msi /lv log.txt
Run through the install until you get the error. That should create a log.txt file that has more information for troubleshooting. The “lv” switches are for logging and verbose. You can see more here https://technet.microsoft.com/en-us/library/bb490936.aspx
Once you have the log file search for any sort of “Error”, and see if that helps.