Hi Stabilo_166
You cannot transfer payware content between installations of Trainz using cdp files.
In this case you will need to delete the assets that are marked as 'installed, payware (not active)' and then download the DLC pack using the in-game Asset Download tool.
However, if the Asset Download tool does not appear automatically, then please click on 'File' on the launcher screen, then click on 'Download Purchased Items', and then click on 'ok' on the message that appears. Now click on 'Start Trainz' on the launcher screen, and you should then see a window appear in Trainz with a list of available downloads. Please click on 'download all' to download the DLC pack.
Regards