Just tried installing the "Victorian Railways Type 17 Wagons Pack" from the DLC and I received the same error message. Not the birthday present you would have been hoping for. I will put in a help desk request.
Just got some feedback from the creator of that asset. They (N3V) are looking into the problem but all the assets in that package are now available on the DLS.
Hi All
This DLC pack was withdrawn from the store a couple of years ago, as it was never updated to work with TANE or newer. Because it was so old, I released all of the assets onto the DLS instead.
The DLC pack version won't install into TRS19 or TRS22, as the DLC pack was never fully updated to the current formats, but you can instead install these assets from the DLS by searching for 'VR I T17' on the DLS (under my personal account's username S301, or userID #103475)