The big difference between the later (v.2) HyperCard "developer's kit" that was sold and the HyperCard client that was given away was the set of manuals, which are not available as PDFs on Apple's servers. They are relatively uncommon, because not everyone fancied him/herself as a "developer." The key one was the Scripting manual, with detailed information re. the commands.

What version of HyperCard are you working with?