To keep the initial download small, the base install includes Kickstarter County 2 plus a range of sessions and tutorials.
STEAM users shouldn't require a MyTrainz account for this to happen but a one-time restart will be required to update the branding to TRS22PE and unlock the Platinum features. If you have the correct TRS22 build installed and you have purchased TRS22PE, then the game should automatically update to the TRS22PE branding and unlock the features in-game once you login with your MyTrainz account.
The build number information is listed on the Trainz Trainz Wiki. Next, you can check to see if you have a compatible TRS22 build installed that enables the Platinum Edition features.
