Thanks for posting her site, she does indeed do lovely work, really gorgeous stuff! Very realistic.
By sugar flowers, well she could mean fondant or gumpaste, likely gumpaste as though fondant holds up for some flowers like roses, for larger ones you are better off with gumpaste or at least a bit of Gum-tex or prepared gumpaste mixed into your fondant.
Sugar could refer to sugar paste which depending on who is using the term can be a general term covering all fondant and gumpaste or strictly fondant.
My suggestion regardless of where you get your instructions from, is to purchase a real calla lily or other flower of the type that you want to duplicate, or a silk version. Actually two would be a good thing. That way you can pull one apart to see the actual construction and have the other one to view as you duplicate it. There are various types and sizes of cutters for most flowers and some do a more realistic job than others. However, you can duplicate just about anything by making your own adjustments.
I have found that you can follow instructions but they are not always as accurate or complete as they should be. For example, they don;t always tell you that you should thin or vein various parts to get them to look more natural and this is why I prefer to have a living or silk version handy.
This is especially true with leaves and I have found that most people make leaves that look like they were just cut out with cookie cutters as the instructions never seem to tell folks to thin out the outer leaves and re-impress the veining with more than just a veining tool.
Hugs Squirrelly Cakes