In this very short clip you can see VCV Rack synced to Bitwig through the bridge plugin and with the help of Expert Sleepers plugin SW Sync.
Of course you can try any of your own clock pulse ideas, and see if that works better for you.
Currently we can not send HW Clock device to the VST next in the chain,
if you would like to see this enabled, bug Bitwig about it (send them email requesting it!).
Mind you this is a quick dirty recording, for demo purpose.
Since this question keeps on popin up all the time here in the forum and on the FB group.
In reality i would not do it like this, first i would have created my idea in VCV.
When i am finished doing that, i would create the sync, preferable through another method (virtual audio patching through my MOTU sound card).
Then i would record the audio as stems in to the daw in this case Bitwig.
While VCV is minimized to the taskbar.
This is what i do most of the time, but not all of the time.
If neither of these 2 methods works for you, then you will need to wait until the official VCV Rack VST comes out.
Hope this is helpful for you.