CO mails paper ballots to everyone* about a month before election day. You can choose to vote in person, or mail in/drop off your paper ballot anytime prior to election night.
My understanding is what while the ballots are paper, many (all?) are tabulated digitally. It certainly appears to be laid out in a way that benefits digital reading, and i believe that is what the machines in question are responsible for.
* for some definition of "everyone"