Installing FreeDOS onto a USB stick using unetbootin fails

As of late, there have been numerous complaints about unetbootin not working. I do not know the specifics, but the end result is usually something like 'no operating system found'.

There is a solution. It's to use a different program. My personal favorite is Balena Echer.

You might also consider Mkusb. There's MultiBootUSB that is more aimed at multiple ISOs on one USB. The list goes on and you can search for alternatives. If you're using Windows, there are even more choices.