You buy it from the Trainz store and then you own it as your own copy of TS2019 and it will be assigned to your My Trainz download page. If like me you had a gold subscription and cancel it you will only have the content bundled with the regional edition once your subscription runs out. I purchased the Uk regional edition because I'm only interested in the Uk scene, but it will be exactly the same for your Europe regional edition.
The base game download stays the same with the US Kickstarter County as a bundled part of it. This is the same for all versions. Once you start up a regional edition for the first time you will get a download window pop up where you can download your game routes according to the version you own. Be aware though that if your gold subscription is still running you will be offered everything that's bundled with the full version of the game.
