The TSM Desktop app is looking for certain files in the WoW directory selected to ensure it's valid. Ensure that you are selecting the directory you are launching the game from, and that you have launched the game at least once before selecting the directory.
Related article: How do I setup the TSM Desktop Application?
Why does the Desktop App say my directory is invalid?
Community Manager
Written by Gumdrops (Community Manager)
Updated at August 3rd, 2021