I’m on pc and use the default ATC too. I would say it’s fine 90% of the time.
To make it work you need to set your flight plan up in the world map. I use simbrief autodownloader to save the flight plan and then simply load that into the world map. As i usually start cold and dark, i have to change the starting point which defaults to the runway, so just select a gate from the drop down list (i find that if you click on the map to do this it will change the flight plan but using the drop down doesn’t seem to do that). Once in the plane, then i upload the simbrief flight plan into the FMC so that is the same as the world map flight plan.
This works pretty well most of the time.
I’m sure there’s lots of scope for improvement though.