Open the mod info and check if all the data for the modded bus is entered. Make sure you did the mod kit setup outlined here.
Exporting and adding to the game
The mod kit has several functions in the Tools section.
First we need to cook our mod. This exports all game files to a format that is readable by the game.
After the cooking is done, use the “Copy to game directory“ button to put the file in the correct folders. Once they are there you should be able to get your bus mod ingame.
Spawning ingame
Once the mod is in the correct folder you should be able to buy your bus at a dealership and use it like any other bus in the game.