To install the add-in, just run the downloaded installer (msi) file. You should run the installer as a regular user, not as an Administrator. Administrator permissions are not required (and won't help).
When you run the installer, it will ask you for a license key. If you are running the add-in as a trial, just click Next to skip this page. Otherwise enter your license key.
When the installer is complete, there's an option (on the last page) to open a walkthrough file which shows the basic functions and features of the add-in. The walkthrough is also available from the Start Menu / Start Screen, or you can download a copy here: Walkthrough.xlsx.
To remove the Add-in, use Add/Remove Programs (Programs and Features) from the Windows Control Panel. Select "RiskAMP Add-in" in the list and click Uninstall.
You can also uninstall from the Windows Start Menu (or Start Screen, on Windows 8 and later) under Programs > RiskAMP > Uninstall.