Question: how to convert nwc to nwd?
Answer: Mike is correct as Navisworks Freedom can only open NWD and DWF files. Rather than open each NWC individually and save to an NWD, if you'd like an automated way to convert your NWC files to NWD files to be opened in Freedom, you can use the Batch Utility (Home > Tools > Batch Utility) in Navisworks.