AThe flowers look big so I doubt there's a cutter the size you want. You could print out hibiscus petal shapes from online, cut them out of the paper, lay them on your fondant and just trace the outline with a knife. That's probably what I would do. Love the design, aloha!
They must have cut each petal out - study the tops of a few of them, some dip down and some point upward. I think I would use a large tulip cutter then slit them as shown in the photo.
My 1st impression was to use a heart cutter but as others suggested the tops of the petals are different. So printing out patterns is probably your best bet.
I agree -- print out your designs and cut the fondant out around it. I would love to do the Cricut thing but I just don't make enough cakes right now that require it to make the investment, so when I need to do something like this, that's what I do. These are larger cutouts, so it shouldn't be too difficult -- just make sure you have a good sharp knife or other cutting tool so your edges are clean.