With all due respect, the In-Game Marketplace is absolutely awful to use — especially the update function.

I constantly have to re-download files over and over, close and restart the game repeatedly, yet it always keeps showing installation failed.

It’s unbelievably clunky and such a torture to deal with.

Same question. I tried repeatedly without success to update the TriStar in the marketplace. Gave up in disgust and am now just waiting to be able to migrate it to the Inimanager.

No eta at this time for it's arrival into the IniManager, was the aircraft selected in the free flight menu when you went to update and install. Most often times this can break the install function and as such can lead to this error. Select a default Cessna or some other aircraft and then try to update and install Tristar again after relaunching the sim. Let me know if this helps.