I have been using a couple of Pronto 980s for years but one is having issues.
I managed to pick up a brand new TSU9600 to play with instead.

I updated the firmware which was 1.xx to the latest version and then installed PEP3 on Windows 11, all working perfectly.

I didn't have to do the "kill process" step above.

I have now installed PEP2 as recommended and again it installed without issue on Windows 11.

I did notice on my laptop, also Windows 11, that I have to disable the touchscreen to download to the remote, my desktop was fine.