SendKeys cannot reliably automate an install. An install package must be designed for "unattended" install or it will fail. Most packages today support switches like /q and /s to cause a silent install. You must
check with the vendor of the package to find out how to do a silent install. It is not a scripting issue and cannot normally be solved via a script.
Microsoft provides MSI (MS Installer) technology which provide good support for silent installs.
¯\_(ツ)_/¯