Trainz Simulator 12 Steam Multiplayer error

I bought Trainz Simulator 12,3 years ago but my pc was sucks. now i bought a better one and i download it, but once i try Multiplayer it says Auran login information and i registered and put them at options.. Now it's says no key in the account. So im lost, the key it's already in steam & i forget it (I forget the key..) also idk what to add in auran panel

NVM,i did it

Lookup the key in your Steam account and register it here:
https://www.auran.com/planetauran/SN_Enter_Serialnumber.php