Hmm, strange. It shouldn't prompt you to install Silverlight anywhere on the 'Create' page.
The only thing available to install from that page is the Photosynth (synther + Direct3D viewer) installer. You may also be prompted to upgrade it if your current version is detected to be out of date.
Anyway, if you want to create a new synth you don't need to come to the website first. After you've installed the synther it can be launched directly from your start menu.