meh, you do what you can to make it work sometimes.
i have a bunch of Minimus AVR boards that i got back in the Kade days... 10 some odd years back, that are already setup to take pin signals going low and turn them into various keyboard key presses. (all configurable) shows up as a USB keyboard to windows. shame they didn't do more... it's was looking like a solid project.
in any case, a program called "atmel flip" will update the bootloader of your arduino so you can upload a keyboard HID file into it, so it just boots directly to HID mode. https://www.instructables.com/How-to-Make-a-Arduino-HID-Keyboard/
I got a working acceptor already with the board I posted earlier, the ardionos I get locally, are either atmega 328 or smd something like that,both are not compatible to turn them into hid keyboards. To bad the original v6 wont work, I really trusted that payway company, but they did not do a good job. I only canhope to get my money back, minus the shipping. I hate when people do that, I mean I'm pretty sure all they did was upload the old firmware and they didn't care about testing them, even though they said they tested them out, its a lie, because once they got to my home, they magically wont work. Freaking liars. If I get my money back , I'm buying another acceptor.