Lets assume you downloaded the 5.1.1 installer from Datasmith Exporter Plugins - Unreal Engine
It will then be in your “Downloads” folder
Then let say you want the log file in a clean empty folder like this one
Then you will have to type and execute
msiexec.exe /i C:\Users\K_J_O_USERNAME\Downloads\UnrealDatasmithMaxExporter_5_1_1.msi /lvx* c:\TempFolder\MaxInstallDatasmithMaxInstall.log
K_J_O_USERNAME => your actual windows user name, in the path to your download folder.
You can find it by looking at the properties on the log file
Once run you should have a log in your folder
Please, create a private message on the forum to me and attach that log file to it.
Bests,
Flavien.