The presets are already preinstalled with FormBuilder. The support pages provide the default presents in the event you were to overwrite the original presets or delete them.
So, if you are just installing FormBuilder now, you don't need to do anything with the preset files.
In the future, if you create new presets or want to import presets from other users, you would just use the WebAssist preset manager which will also get installed with your extension.
Best regards,
Brian