I’d recommend making a copy of your Artemis directory {as downloaded from Steam} and five it a “friendly name” {like TSN-Dec}. GO in to there and create a shortcut {I put mine on my desktop_ to Artemis.EXE. Test launch and it should show Artemis v 2.2 (as downloaded from Steam).
Go HERE to get the v 2,1,1 “upgrade”.
Run this EXE and point it to the new folder {TSN-Dec, or whatever you called it.} Use Shortcut, should now report itself as v 2.1.1.
Go HERE to get the TSN mod.
unzip it into the TSN-Dec folder, overwrite as needed.
Launch again, should say v 2.1.1 w/ TSN mod v 1.1.3 {currently}. Do that, and you ready to fly.