You can buy a "backwards compatible" board for about $130. The instructions for changing it are excellent.
I actually sold my old AC and the "new board that I had to remove".
The board lets the AC unit work with the existing 5 button thermostat.
The worst part of the installation is getting an AC unit that is not physically damaged. The box may not show damage but they can look like a train wreck inside.
Two people can change the unit in half a day including the new board.
I have no idea why they think the data line needs replacing. Clean the old ones gently and they should work.
Myron & Deborah
08 HR Endeavor 40 SKQ
400 Isl, 400 HP/// Now 450 HP
2016 Ford F150 Limited V6 with Ready Brake