PDFJinja object creation using file stream/object. about pdfjinja HOT 1 OPEN

I am getting the below error, when I tried to use example.py code from the pdfjinja project.

Traceback (most recent call last):
File "P:\Professional\Python\CR\workspace\workspace-local\myplaybook\pdf_pdfjinja.py", line 10, in
rendered_pdf = template_pdf({
File "P:\Professional\Python\Softwares\python-3.9.6\lib\site-packages\pdfjinja.py", line 240, in call
filled = PdfFileReader(self.exec_pdftk(self.rendered))
File "P:\Professional\Python\Softwares\python-3.9.6\lib\site-packages\pdfjinja.py", line 212, in exec_pdftk
p = Popen(args, stdin=PIPE, stdout=PIPE, stderr=PIPE)
File "P:\Professional\Python\Softwares\python-3.9.6\lib\subprocess.py", line 951, in init
self._execute_child(args, executable, preexec_fn, close_fds,
File "P:\Professional\Python\Softwares\python-3.9.6\lib\subprocess.py", line 1420, in _execute_child
hp, ht, pid, tid = _winapi.CreateProcess(executable, args,
FileNotFoundError: [WinError 2] The system cannot find the file specified

from pdfjinja.