Canon ImageClass MF4770n will not work without proprietary software, it seems.

At my workplace we have a Canon Imageclass MF4770n printer that we've had for several years but stopped using at some point for some reason. I wanted to try to get it working with Trisquel, but it seems like I won't be able to without installing proprietary software from Canon.

I found a Canon website that lists the printer [1], and the UFR II printer driver package contains a free ppd file, but when I try to add the printer with the ppd file, I get an error message saying that /usr/lib/cups/filter/rastertoufr2 is required, and this seems like a proprietary file included in the Canon driver package.

Curiously, on Microsoft Windows the printer says "Driver is unavailable", and the printer is not shown as an option in Chrome. Additionally, the Canon website I linked does not even provide a driver for Windows. So maybe I am missing something important, because it would seem surprising if the printer does work with Windows, especially when I think it did in the past.

It seems like the printer requires installing proprietary software in order to print from Trisquel. Does anyone know if whether I have come to the correct conclusion?

[1] https://in.canon/en/support/imageCLASS%20MF4770n/model