After running the installer for the bonus fonts, you will find a folder within your Documents folder called Summitsoft Fonts, which in turn contains a folder called Creative Fonts Valentines.
This folder contains 35 OTF files (OpenType Fonts).
Use the Windows file manager and go to the folder (Documents\Summitsoft Fonts\Creative Fonts Valentines), select whichever fonts you want to install, or click on one and press Ctrl-A to highlight them all.
Then right-click on a selected font, and choose Install.
These fonts will now be available within the Hallmark Card Studio program as well as other Windows applications.