Trackmania 2 Valley Key Problem

[Normala]

Hello guys, i bought key via g2a, and i start the game. When i first time start the game i need to create an account on maniaplanet. After i login with new account creation, the games says that i need to enter a key or buy , i am litle bit confused becouse i have game on steam. I found a key on steam and i enter a game and tryed to put the key ingame but error pop up. (This game key requires Steam.) I dont know what to do can anyone help me please.