Hello,
the PDF printer only knows the folder of the original file if the program you print from sends the full file path with the print job. Many programs only send the file name. If the path is sent, "Save" in the PDF24 Assistant (the window after printing) opens in the folder of the original file, unless a "Fixed save directory" is set on the "Assistant" page of the settings. Automatic saving of the PDF printer always uses the folder set there.
For the tools of the PDF24 Toolbox such as "Sign PDF" or "Edit PDF", the save dialog currently opens in the folder used last. With the next version it suggests the folder of the original file.