SeedCode Complete requires FileMaker Pro 11 or higher. The solution does not use any plugins or other trickery for its basic functions. This is a simple FileMaker solution like any you'd make yourself, perhaps just a little further along.
If you're using an older version of FileMaker you can download a 30 day trial of FileMaker 11 here: http://www.filemakertrial.com
You can share SeedCodeCalendar with up to 9 guests without FileMaker Pro Server, providing each guest as a copy of FileMaker Pro. Even with a small number of guests, however, we strongly recommend you use FileMaker Pro Server for the best possible performance. FileMaker server also offers increased crash protection and provides for the scheduled backup of your databases, making it invaluable in our estimation, and it offers one of the easiest ways to schedule email notifications.
Instant Web Publishing Requirements
Note that to publish Complete via Instant Web Publishing you'll need to create your own layouts that are IWP friendly. Elaborate layouts like those in Complete do not "just work" in IWP.