The contact form solution pack is not an extension.
In your order history, it shows you purchased CSS Form Builder. This extension includes the Validation toolkit and UE functionality.
log into your account and go to the downloads section of the MyAccount page. Click the all my downloads link to access downloads for previous versions.
on the All My Downloads page, you will find the download for CSS Form Builder
download the CSS Form Builder MXP File, then open the Extension manager, click the install link and browse to the MXP file you downloaded.