"is necessary to have Acrobat Professional to use PDF Generator in workbench? "
It depends which transformation you're planning to use. If you're planning to convert to PDF, then yes you need Acrobat installed.
Yes, I converting to PDF.
I installed Acrobat pro extended, but it didn´t help.
As output of htmlToPDF component is "this document type can not be recorded". Is possible the webpages have to have some special structure? Can you give me some webpage which is posible generate to PDF?