It depends on the plane your using. When I tried it on the C172, it straight imported it into the C172’s avionics the second you click import route. But if your using an inibuilds plane like A330 or Beluga, you still have to use the planes EFB to import the plan from simbrief after you use the simbrief dispatch app MSFS24’s EFB to import the flight plan. Its a little confusing
What plane are you using it with?