Hello ,
Thank you for posting in the community and typically after restarting the computer and reopening Twinmotion and Archicad the link is found. Make sure to go into Twinmotion and select the import direct-link option first and select the source. Here is a video that shows the steps to establish a direct-lnk connection with the Datasmith Exporter plugin: https://youtu.be/m3fQvegazzY
For reference here is an overview article:
https://twinmotionhelp.epicgames.com/s/article/Getting-Started-using-Datasmith-Workflows-with-Twinmotion
If you are still having issues there could be something else interfering with the connection and we would need to investigate further with you to help troubleshoot this problem. Please follow this link to report a bug here: https://twinmotionhelp.epicgames.com/s/case-community-page
Kind regards,
Vincent B.