By default, the clip art gets installed to your Documents folder, into a folder called Summitsoft Clipart, then a folder inside it called Creative Collection 4.
This folder contains a number of subfolders with all of the clip art arranged by category.
A PDF file is provided (Creative Collection 4 Help.pdf), with thumbnail sheets of the clip art graphics.
To use the clip art within the Hallmark Card Studio 2018, use the Insert Picture tool, and then browse to the folder and choose the clip art you want.