On osC 2.3.4 and with the current version of tcpdf, this module will NOT work out of the box. As the author, who has blocked the add-on from public uploads, cannot be reached for comment, I thought I'd post my findings here.
Open the User Manual .pdf and go to page 7, paragraph 2.2.4 "The FPDF Library Files" 1) After this, in your shop root, create an additional directory ext/tcpdf/config/lang From the unpacked FPDF archive, copy tcpdf/examples/languages/eng.php to the new directory you have just created. This package will NOT function without it. 2) Go to your store’s Administration Section, Modules, PDF Datasheet and use the following sort order in order to avoid seemingly missing pieces of information in the generated PDF: Disable: Features, Image and Price, Product Page Link, Specifications Enable: Initialise 9000 Header 9001 Fonts 9002 Title 9010 Manufacturer’s Name 9045 Description 9050 Extra Images 9060 File Name 9999