The chassis manufacturer, in this case Mercedes-Benz, normally determines alignment specifications. If your tire shop even cannot go to a Mercedes source and obtain the alignment specs, that is scary. I don’t think you should trust them to do a front end alignment. Go to a reputable truck tire and alignment business that does these alignments regularly, they will have the specs, and you’ll be better off (hopefully) getting the work done right.
In our case Forest River paid for the alignment on our new Sunseeker (Ford). I don’t know if they do that over at Dynamax, but you could ask.
2020 Sunseeker 2440DS on 2019 Ford E-450, Trekker cap, Topaz paint