Just tested this, and it doesn't happen here.
It was a problem only in the initial release, and it was a texture.cfg file missing in SOME Crew models, used ONLY when the airplane airline wasn't recognized, likely because the airplane is missing the icao_airline from the aircraft.cfg or, in this case, because the aircraft.cfg can't be read, because the airplane is sold on the MS Marketplace, so those planes will ALWAYS get a generic uniform UNLESS you have a FlightPlan on Simbrief with a recognized airline code, in that case the airline code will be taken from Simbrief, so that would allow Marketplace airplanes to get correct airline uniforms as well.
In any case, I verified that even the generic uniform should work, because one of the affected files is this one, which is the one missing in the OP picture:
Addon Manager\MSFS\fsdreamteam-gsx-pro\SimObjects\GroundVehicles\FSDT_Crew\texture.FSDT_Attendant_hs2\texture.CFG
Which was missing in the initial release, so I removed it, started the FSDT Installer again, clicked the CHECK button, and the installer downloads it again.