At least for the moment, SUCCESS!
Navigating to "OneDrive-Personal" in File Explorer, I selected Settings. Under the "Sync and backup" tab, I selected "Manage backup" and turned off everything. Then, still in the Settings, I selected "Account" / "Choose folder", where I was able to deselect Documents.
That process left me with two Documents folders, one under OneDrive, the other, now without much of anything in it, under "This PC". I still had the Juicebox install file in my Downloads file, so I reran the install, which ended up in the "real" Documents folder under "This PC". I was able to open an existing directory, and the hoped-for editing options appeared. Meanwhile, there is no longer a Documents folder in OneDrive, but as far as I know, there really wasn't anything significant in it before I disconnected the link with OneDrive.
This experience tells me that OneDrive is structured in a way that is fundamentally at odds with putting the user in control of the PC. It gets in the way of ordinary management of what is on your PC. I think it may be designed for too many, contradictory purposes that are entangled, when logic would dictate that they ought to be separate but able to communicate with each other when requested by the user.