When starting a new 4D project, you must decide whether the 3D models will be imported via the 3D importers in SYNCHRO 4D Pro or whether the models will be bridged into the iModel using the iModel Connections workflow. For help deciding which workflow to use, see this topic
If you have decided to work with the iModel Connections:
For more information on creating iModel connections, see this article
To edit the connections or synchronize updated model files, see Synchronizing updated 3D Models
Quick link to iTwin Services iTwin Synchronizers wiki: https://communities.bentley.com/products/digital-twin-cloud-services/itwin-services/w/synchronization-wiki
iModel publishing best practice: https://communities.bentley.com/products/digital-twin-cloud-services/itwin-services/w/synchronization-wiki/50654/imodel-publishing-best-practice
NEXT: Adding users to a SYNCHRO Control project and managing permissions