When I want Create/Edit PDF Template I get a blank page in the browser/crm area.

Please, check the all Vtiger parameters: https://it-solutions4you.com/tipstricks/vtiger-system-requirements/

You can also try performing the following steps:

  1. Please download following zip file: http://its4you.sk/images/extensions/PDFMaker/src/ckeditor.zip
  2. Then go to the folder vtigerdirectory/modules/PDFMaker/resources.
  3. Rename folder ckeditor to ckeditorOLD.
  4. Open the zip file and copy ckeditor from zip file to this folder.
  5. Next go to the CRM, clear browser cache and try again.