That's my question too. Must be they weren't able to connect to the site that changes the votes from Republican to Democrat.
In Louisiana, voter registration is checked before you are allowed to vote. On election day, most precincts use a printed roll to check and you must sign your name next to your entry. I don’t know for early voting. They may use the internet to verify registration as the smaller number of early voters to election day voters would make the paper list harder to accomplish.
Valid picture IDs are also required, but one can vote without one by filling out an affidavit.
Likely a VPN (Virtual Private Network) over the internet to the Elections Mother-Ship Server. That is an encrypted pipe. Very common way to set up a Temporary Location. Simple, we did it all the time in my Corporate IT days