A (Printer File) is not a standard document like a PDF or Word file. It is a set of specific instructions intended for a printer to interpret.
The .prn extension belongs to the era of LPT ports, of daisy-wheel printers and green-bar paper. That such a file can still be generated—and downloaded—reveals that the past is not erased. It is merely queued, waiting for the right interpreter to come along. Dccv1-51-prn File Download
Leave the user and password fields blank (hit Enter for both). Type put , then drag and drop the .prn file into the window. A (Printer File) is not a standard document