It is very loosely inspired by It, but you're right that there's no supernatural elements nor anything scary in the base game!
The page for Other Summers wasn't ready, it is now :) The supplement will be released next fall!
So, Other Summers has a page but isn't ready to download, right?
That's right! The supplement is in the works; I'm translating it from French this summer and then it's off to layout. As I wrote, it should be ready for release next fall!