These folders contain add-ons for webtrees submitted by users.
They are not included with the official release of webtrees, and are not maintained by the webtrees development team. Any queries you have regarding these should first be to the creator directly. If that doesn't work, you can can try the Customising page of the Forum here. For the more popular items you might also find they have their own sub-category of the forum.
Note that all webtrees 1.6.x modules or themes will not run on webtrees version 1.7.x unless specifically noted.
Click on the name of any item to see its full description.
To download webtrees itself click on Launchpad > Download from the menu at the top of this page.