For running J!5.1 you must https://fabrikar.com/forums/index.php?wiki/update-from-github/ or include the new file manually https://fabrikar.com/forums/index.php?threads/joomla-5-1-and-fabrik-cannot-find-files-error.54473/post-285151 See also Announcements
Please see our announcement here.
JResponse::setHeader('Content-Disposition', "attachment;filename=\"" . $name . ".doc\"");
$this->document->setMimeEncoding('text/html; charset=Windows-1252', false);
* MS Word/Open office .doc Fabrik Form view class
* Very rough go at implementing .doc rendering based on the fact that they can read HTML