Accessible Tabs uses a very simple and flexible HTML markup as it's base to build upon. All it needs it's a wrapper containing Headlines and content elements one after the other. This provides a nice non-javascript fallback that does not look like something is missing or broken.
In dca/tl_content.php in line 46 it must be
instead of
Currently the input field is not rendered in opener and the standard value of the config isn't used so it produces an javascript error