A responsive template is a template which adapts automatically to different screen sizes (e.g. showing/hiding module positions or displaying one below the other instead side by side...)
Fabrik3.1 templates need a "Bootstrap" Joomla template (e.g. the protostar template coming with Joomla).
You can find the "old" templates in the folder components\com_fabrik\views\list\tmpl25. If you copy them to \tmpl you can use them
BUT
a lot of CSS is missing.
In my view fabrik should support the old "standalone" templates, too, not forcing the use of a special Joomla template.
We have a lot of customers using the old Joomla1.5 templates in Joomla2.5 without problems, we have several Joomla2.5 sites running with responsive templates (not using the bootstrap framework) and I really fear the moment where we have to upgrade to Joomla3.x (3.5+) and are forced to adapt all those templates because of Fabrik.