Not really following you. Was there suppose to be something to download and reference? If so, nothing was attached to your post.
Regarding the add-in: I presume you are speaking about the Timber Frame Extension and it's unavailability, as yet, for 2018. Previous versions of Timber have also lagged behind Revit version upgrades - typically by many months. I suspect it's forthcoming.
All this guessing aside: what are the details of your specific issue? 99% of what Timber Frame Extension does, can be done without using it - and somethings, even better.