It is the first time I have this weird issue. The PDF file is downloaded online but can not print as normal.
OctoPrint is a print host for 3D printers. It does not handle PDF files at all. In other words, this is not the forum for your problem. But to help you a bit further, here's a link to a search engine:
There is a way to print a pdf with a 3d printer:
Convert the pdf into a series of images and create stl on http://3dp.rocks/lithophane/
OP would still have to open the password-protected PDF though.
My reply was a tongue-in-cheek suggestion regarding "It does not handle PDF files at all." The problem of password protection was sufficiently solved by your search link.
I can open the pdf but can not print. it seems not the open password attached to it.
Update: The issue was fixed with the help of this tutorial: https://www.passgeeker.com/remove-password-from-pdf.html
I am sorry, I really can't help you with printing PDFs on a "2d" printer.
I'm not sure if you you're a bot or a real person.
I guess you're waiting for a request to upload your pdf and it's going to be malicious in some way.
As @fieldOfView said - this is a software for 3D printers and not for inkjet or laser printers.
I'm closing this thread now.