If TUG crashes when you launch it through Steam but will run when you go into the TUG folder and launch the executable manually, it is possible that the Steam overlay is interfering with your game's launch.
You can turn off the Steam overlay for individual games and we recommend doing this for TUG if you run into this issue.

To disable the Steam overlay for TUG, go to your Steam game library, right click TUG in your library and select "properties". Un-check the box next to "Enable the Steam Overlay while in-game" and click close. This should resolve this issue.