Delta Drive, Delta Trust & My Drive · Linked folders and copies
How do I keep a copy of my Mac's Documents folder in Delta Drive?
Short answer: Open Documents, Desktop or Pictures in Delta Drive and press Keep a copy of my Documents here (also on the right-click menu and Copies screen). It's then kept up to date; turning it off leaves the copy in place.
Open Documents (or Desktop or Pictures) in Delta Drive and, while it's still empty, press Keep a copy of my Documents here. The same switch is on the folder's right-click menu and on the Copies screen.
Nothing is copied until you press it. After that the copy is kept up to date as the folder changes, and Copy … now does it on the spot. Turning it off leaves what's already in your drive alone — it just stops being kept current.
This is different from backing the same folder up to Delta Trust. See the two sets of switches.