Sharp printer MX-3610N not working with Mojave?

[PowerMacBook]

We have a Sharp MX-3610N multi functional printer/scanner network printer.
I cannot print to it.
It does show up, installed the driver, choose the printer etc.
When doing a test print, it does connect to the printer, wakes it up, etc but other then noise it fails to print any paper.
The Readme-file mentions if using Mojave the firmware needs to be updated.
However, I cannot find the firmware.

Does anyone has an idea how to approach this, or where to find the proper firmware?

Thanks.