In R2023b that command loads the example for me even though I do not have several of the required toolboxes installed; https://www.mathworks.com/help/supportpkg/px4/ref/hitl-simulink-fixed-wing-plant-example.html . It did, however, need an internet connection to load it in.
Which MATLAB release are you using? And do you have all of the necessary toolboxes installed, as listed in the above link?
