I am using the freeware version and do not have access to this option. Furthermore this is a dialog which doesn't come up at other installations. I am trying out this installer so please help so I can convince my staff to buy it.
I just found out this dialog is due to using the commandline option MSIEXEC.exe /a package.msi. I also found the solution by using the '/i' instead '/a' option for this. So MSIEXEC.exe /i package.msi works well.
You don't need to run msiexec.exe to install your application. Just double click on the .msi file. It will automatically run msiexec.exe /i package.msi for you.