As far as I know Dorico cannot slave to timecode, but there is a way to have Dorico be the master and send it. MTC requires a third party plug in called TXL Timecode Plug-in.
It’s also possible to send SMPTE/LTC over an audio output using the video player if you have the black boxes or software to use that method.
There are several threads on the topic (getting Dorico to transmit MTC/SMPTE/ETC) throughout the forum. Check out this one:
For others do some searches similar to this one:
Search results for ‘mtc #dorico’ - Steinberg Forums