Fix - Go to Ubisoft Connect Download Page[ubisoftconnect.com]. Download and install Ubisoft Connect, and create or log in to a Ubisoft Connect Account. Then, close Ubisoft Connect and Launch Trackmania Turbo. If it worked right, it should say 'Do you want to bind Trackmania Turbo to your Ubisoft account' or something along the lines of that. Click 'Bind' and it should launch Trackmania Turbo. If it doesn't, go back to Steam and click play again.

(By the way, Ubisoft Connect is just a newer version of Uplay.)