The best way is to give them a call. They need the calibration number of your engine computer so they can send you a matching one.
The number is usually on a sticker on the ECU. You can also have them send you a programmer and use that to read the number out of the engine.
Once they have the number they will send you the calibration (either in an e-mail as a file or send you the programmer if they haven't already).
The programmer is included in the price of the tune--in my F-350 case it was an SCT X3 (looks like they now use an X4).
1. Ford 1996-2016 6.8L V10 RV / Motor Home ONLY! SCT X4 with the 5 Star Tune - 5 Star Tuning
They can also make the tune custom for you (like moving a shift point--one person on the Ford Trucks forum had them make it hold the gear a bit longer to avoid certain gear hunting situations).