Where can I get this train?

You mean this one?

<kuid2:212731:20000149:1> PT DB BR 52

You can purchase this payware locomotive if you have TRS19 or higher.

This is made by the same guys that created the original. Note the PT in the name for Pro-Train.
The BR52 referred to in #1 is a payware locomotive "BR52 4544" from Steam Locomotive Works.